Perovskite solar cell, liquid composition, and method for manufacturing perovskite solar cell

Abstract

Provided are: a perovskite solar cell excellent in durability; a liquid composition suitably used for forming a photoelectric conversion layer in manufacturing of the perovskite solar cell; and a method for manufacturing the perovskite solar cell using the liquid composition. A perovskite solar cell (1) comprises, in the given order, the following: a first electrode layer (20), a hole transport layer (30), a photoelectric conversion layer (40), an electron transport layer (50), and a second electrode layer (60). Contained between the first electrode layer (20) and the second electrode layer (60) is: at least one compound selected from the group consisting of ascorbic acid compounds, phenolic compounds, and unsaturated compounds; at least one oxygen atom-containing compound selected from succinic acid compounds and phosphorus compounds; or diphosphorus pentoxide.

Description

Perovskite solar cell, liquid composition, and method for manufacturing a perovskite solar cell

[0001] The present invention relates to a perovskite solar cell, a liquid composition, and a method for manufacturing a perovskite solar cell.

[0002] The use of solar cells is expanding as an energy source with a low environmental impact. When installing solar cells in various devices, vehicles, buildings, etc., the available installation area is limited, so the photoelectric conversion efficiency of the solar cells can be important. Perovskite solar cells, which use organic materials, are being researched as solar cells with high photoelectric conversion efficiency. A basic perovskite solar cell consists of a substrate on which a first electrode (anode or cathode), a charge transport layer (hole transport layer or electron transport layer), a photoelectric conversion layer (perovskite layer), a charge transport layer (electron transport layer or hole transport layer), and a second electrode (cathode or anode) are stacked in this order.

[0003] Furthermore, Patent Document 1 describes a solar cell in which a monolayer is formed on the surface of a first electrode laminated on a substrate, a photoelectric conversion layer is directly laminated on the monolayer, and an electron transport layer and a transparent electrode are further laminated.

[0004] Japanese Patent Publication No. 2010-141165

[0005] However, in perovskite solar cells with the structure described above, various organic compounds are used in each layer that makes up the solar cell. Organic compounds are generally susceptible to modification, degradation, or decomposition due to the effects of light, oxygen, moisture, etc. Due to this instability of organic compounds, there is room for improvement in terms of durability in perovskite solar cells.

[0006] The present invention has been made in view of the above problems, and aims to provide a perovskite solar cell with excellent durability, a liquid composition suitably used for forming a photoelectric conversion layer in the manufacture of the perovskite solar cell, and a method for manufacturing a perovskite solar cell using the aforementioned liquid composition.

[0007] The present invention includes inventions A, B, and C, as described below. Each of these inventions includes various embodiments, as described below.

[0008] <Invention A> The perovskite solar cell according to the first aspect of Invention A includes a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order. Between the first electrode layer and the second electrode layer, one or more compounds selected from the group consisting of ascorbic acid compounds, phenolic compounds, and unsaturated compounds are included. The ascorbic acid compound is represented by the following formula (1a): (In formula (1a), R １ , and R ２ are each independently a hydrogen atom or a monovalent organic group, and R ３ is a hydrogen atom, a monovalent organic group, or an alkali metal atom, and R ４ is a hydrogen atom or a monovalent organic group.) The unsaturated compound is represented by the following formula (1b) or the following formula (1c): R ５ -CO-O-CH ２ -CH = C(CH ３ ) ２ ...(1b) R ６ -O-CHR ７ -CH = C(CH ３ ) ２ ...(1c) (In formula (1b), R ５ is a monovalent organic group. In formula (1c), R ６ , and R ７ are each independently a monovalent organic group, and R ６ and R ７ may be bonded to each other to form a ring.) The perovskite solar cell is one or more compounds selected from the compounds represented by the formula.

[0009] In the above perovskite solar cell, ascorbic acid may be included as the compound represented by the above formula (1a) between the first electrode layer and the second electrode layer.

[0010] In the perovskite solar cell described above, between the first electrode layer and the second electrode layer, a phenolic compound is used, such as 2,6-di-tert-butyl-p-cresol (BHT), p-methoxyphenol, 4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole, 2-tert-butyl-4-hydroxyanisole, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol, 4,4'-thiobis(3-methyl-6-tert-butylphenol), tocopherol, and bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propion The acid may contain one or more selected from the group consisting of (ethylenebisoxy)bisethylene (Irganox 245, manufactured by BASF Japan), pentaerythritol tetrakis[3-[3,5-di(tert-butyl)-4-hydroxyphenyl]propionate], bis[3-[3,5-di(tert-butyl)-4-hydroxyphenyl]propionic acid]thiobisethylene, octadecyl-3-(3,5-di-ter-butyl-4-hydroxyphenyl)propionate, octyl-3-(3,5-di-ter-butyl-4-hydroxyphenyl)propionate, 2,4,6-tris(4-hydroxy-3,5-di-tert-butylbenzyl)mesitylene, and 2,4-bis(octylthiomethyl)-6-methylphenol.

[0011] In the perovskite solar cell described above, 3-methyl-2-butenyl acetate and / or 4-methyl-2-(2-methyl-1-propenyl)tetrahydropyran may be included as an unsaturated compound between the first electrode layer and the second electrode layer.

[0012] In the perovskite solar cell described above, one or more compounds selected from the group consisting of ascorbic acid compounds, phenolic compounds, and unsaturated compounds may be included in the photoelectric conversion layer.

[0013] In the perovskite solar cell described above, the first electrode layer is laminated on a substrate, the shape of the substrate is plate-like or sheet-like, and the substrate may be at least one of metal, resin, or glass.

[0014] In the perovskite solar cell described above, the first electrode layer is stacked on a substrate, and the perovskite solar cell may be a tandem solar cell comprising a silicon semiconductor substrate as the substrate.

[0015] A liquid composition for forming a photoelectric conversion layer in a perovskite solar cell according to a second aspect of the present invention A comprises (A) lead halide and / or tin halide, (B) formamidine hydrohalide and / or methylamine hydrohalide, (C) organic solvent, and (D) one or more compounds selected from the group consisting of ascorbic acid compounds, phenolic compounds, and unsaturated compounds, wherein the ascorbic acid compound is of the following formula (1a): (In formula (1a), R １ , and R ２ Each is independently a hydrogen atom or a monovalent organic group, R ３ R is a hydrogen atom, a monovalent organic group, or an alkali metal atom. ４ is a hydrogen atom or a monovalent organic group.) The compound is represented by the following formula (1b) or formula (1c): R ５ -CO-O-CH ２ -CH=C(CH ３ ) ２ ... (1b) R ６ -O-CHR ７ -CH=C(CH ３ ) ２ ... (1c) (In equation (1b), R ５ is a monovalent organic group. In formula (1c), R ６ , and R ７ Each of these is an independently monovalent organic group, R ６ and R ７ This is a liquid composition comprising one or more compounds selected from the compounds represented by (which may be bonded together to form a ring).

[0016] The above-mentioned liquid composition may contain one or more selected from the group consisting of (E) cesium halide, (F) passivation material, and (G) hole transport material.

[0017] A third aspect of the present invention A is a method for manufacturing a perovskite solar cell comprising a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order, wherein the photoelectric conversion layer is formed by removing volatile components from a coating film containing the liquid composition according to the second aspect.

[0018] <Invention B> A perovskite solar cell according to a first aspect of Invention B comprises a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order, wherein one or more oxygen atom-containing compounds selected from succinic acid compounds and phosphorus compounds are contained between the first electrode layer and the second electrode layer, and the succinic acid compound is of the following formulas (1) to (4): (In equation (1), R １ , and R ６ Each of these is independently a hydrogen atom, a monovalent organic group, or an alkali metal atom. In formulas (1) to (4), R ２ ~R ５ , R ９ ~R １２ , and R １５ ~R ２２ Each is independently a hydrogen atom or a monovalent organic group. In formula (2), R ７ , R ８ , R １３ , and R １４ Each of these is independently a hydrogen atom or a monovalent organic group. ７ , R ８ , R １３ , and R １４ At least one of them is a monovalent organic group. In formula (4), R ２３ ) is a hydrogen atom or a monovalent organic group. ) is one or more compounds selected from the compounds represented by the following formula (I) or formula (II): O=P(OR １０ ) ３...(I), P(OR １１ ) ３ ...(II) (In formula (I), R １０ Each of these is independently a hydrogen atom, a monovalent organic group, or an alkali metal atom. In formula (II), R １１ Each of these is independently a hydrogen atom, a monovalent organic group, or an alkali metal atom.) This is a perovskite solar cell, which is one or more compounds selected from the compounds represented by ).

[0019] In the perovskite solar cell described above, the oxygen atom-containing compound may include, as a succinic acid compound, dialkyl succinate and / or N-alkylsuccinimide.

[0020] In the perovskite solar cell described above, the oxygen atom-containing compound may include one or more compounds selected from the group consisting of phosphoric acid, phosphorous acid, trialkyl phosphate, and trialkyl phosphate as the phosphorus compound.

[0021] In the perovskite solar cell described above, an oxygen atom-containing compound may be included in the photoelectric conversion layer.

[0022] In the perovskite solar cell described above, the first electrode layer is laminated on a substrate, the shape of the substrate is plate-like or sheet-like, and the substrate may be at least one of metal, resin, or glass.

[0023] In the perovskite solar cell described above, the first electrode layer is stacked on a substrate, and the substrate is a silicon semiconductor substrate, which may be a tandem solar cell.

[0024] A liquid composition for forming a photoelectric conversion layer in a perovskite solar cell according to a second aspect of the present invention B comprises: (A) lead halide and / or tin halide; (B) formamidine hydrohalide and / or methylamine hydrohalide; (C) organic solvent; and (D) oxygen atom-containing compound, wherein (D) oxygen atom-containing compound is one or more selected from succinic acid compounds and phosphorus compounds, and the succinic acid compound is of the following formulas (1) to (4): (In equation (1), R １ , and R ６ Each of these is independently a hydrogen atom, a monovalent organic group, or an alkali metal atom. In formulas (1) to (4), R ２ ~R ５ , R ９ ~R １２ , and R １５ ~R ２２ Each is independently a hydrogen atom or a monovalent organic group. In formula (2), R ７ , R ８ , R １３ , and R １４ Each of these is independently a hydrogen atom or a monovalent organic group. ７ , R ８ , R １３ , and R １４ At least one of them is a monovalent organic group. In formula (4), R ２３ ) is a hydrogen atom or a monovalent organic group. ) is one or more compounds selected from the compounds represented by the following formula (I) or formula (II): O=P(OR １０ ) ３ ...(I), P(OR １１ ) ３ ...(II) (In formula (I), R １０ Each of these is independently a hydrogen atom, a monovalent organic group, or an alkali metal atom. In formula (II), R １１ Each of these is independently a hydrogen atom, a monovalent organic group, or an alkali metal atom.) The compound is one or more compounds selected from the compounds represented by ).

[0025] The above-mentioned liquid composition may contain one or more selected from the group consisting of (E) cesium halide, (F) passivation material, and (G) hole transport material.

[0026] A third aspect of the present invention B is a method for manufacturing a perovskite solar cell comprising a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order, wherein the photoelectric conversion layer is formed by removing volatile components from a coating film containing the liquid composition according to the second aspect.

[0027] <C of the present invention> A perovskite solar cell according to a first aspect of the present invention C comprises a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order, wherein phosphorus pentoxide is contained between the first electrode layer and the second electrode layer.

[0028] In the perovskite solar cell described above, phosphorus pentoxide may be included in the photoelectric conversion layer.

[0029] In the perovskite solar cell described above, the first electrode layer is laminated on a substrate, the substrate is plate-shaped or sheet-shaped, and the substrate may be made of metal and / or resin.

[0030] In the perovskite solar cell described above, the first electrode layer is laminated on a substrate, the shape of the substrate is plate-like or sheet-like, and the substrate may be at least one of metal, resin, or glass.

[0031] In the perovskite solar cell described above, the first electrode layer is stacked on a substrate, and the substrate is a silicon semiconductor substrate, which may be a tandem solar cell.

[0032] A liquid composition for forming a photoelectric conversion layer in a perovskite solar cell according to a second aspect of the present invention C is a liquid composition comprising: (A) lead halide and / or tin halide; (B) formamidine hydrohalide and / or methylamine hydrohalide; (C) organic solvent; and (D) phosphorus pentoxide.

[0033] The above-mentioned liquid composition may contain one or more selected from the group consisting of (E) cesium halide, (F) passivation material, and (G) hole transport material.

[0034] A third aspect of the present invention C is a method for manufacturing a perovskite solar cell comprising a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order, wherein the photoelectric conversion layer is formed by removing volatile components from a coating film containing the liquid composition according to the second aspect.

[0035] According to the present invention, it is possible to provide a perovskite solar cell with excellent durability, a liquid composition suitably used for forming a photoelectric conversion layer in the manufacture of the perovskite solar cell, and a method for manufacturing a perovskite solar cell using the aforementioned liquid composition.

[0036] This is a schematic cross-sectional view showing the configuration of an embodiment of the solar cell according to the present invention. This is a flowchart showing the procedure of an embodiment of the solar cell manufacturing method according to the present invention.

[0037] <Embodiment of Invention A> Hereinafter, an embodiment of Invention A will be described with reference to the drawings. Note that the dimensions of various components in the drawings have been adjusted for ease of viewing. In addition, in embodiments described later, the same reference numerals are used for components similar to those in embodiments described earlier, and redundant explanations may be omitted.

[0038] Figure 1 is a schematic cross-sectional view showing a preferred configuration of a perovskite solar cell 1 according to an embodiment of the present invention A. The perovskite solar cell 1 comprises a plate-shaped or sheet-shaped substrate 10, a first electrode layer 20 laminated on one main surface of the substrate 10 (the lower side in Figure 1), a hole transport layer 30 laminated on one side of the first electrode layer 20, a photoelectric conversion layer 40 laminated on one side of the hole transport layer 30, an electron transport layer 50 laminated on one side of the photoelectric conversion layer 40, and a second electrode layer 60 (cathode) laminated on one side of the electron transport layer 50.

[0039] A passivation material (not shown) may be present on the surface and / or inside the photoelectric conversion layer 40.

[0040] In the perovskite solar cell 1, one or more compounds selected from the group consisting of ascorbic acid compounds, phenolic compounds, and unsaturated compounds are included between the first electrode layer 20 and the second electrode layer 60. These compounds share the common characteristic of being reactive with oxygen.

[0041] Hereinafter, in the specification of this application, "one or more compounds selected from the group consisting of ascorbic acid compounds, phenolic compounds, and unsaturated compounds" will also be referred to as "specific additives."

[0042] In other words, in the perovskite solar cell 1, the above-mentioned specific additive is present in at least one of the following locations: inside the hole transport layer 30, inside the photoelectric conversion layer 40, inside the electron transport layer 50, between the first electrode layer 20 and the hole transport layer 30, between the hole transport layer 30 and the photoelectric conversion layer 40, between the photoelectric conversion layer 40 and the electron transport layer 50, and between the electron transport layer 50 and the second electrode layer 60. Of these embodiments, from the viewpoint of the perovskite solar cell having excellent durability, it is preferable that the above-mentioned specific additive is present inside the photoelectric conversion layer 40.

[0043] Ascorbic acid compounds are compounds represented by the following formula (1a).

[0044] In formula (1a), R １ , and R ２ Each of these is independently a hydrogen atom or a monovalent organic group. ３ R is a hydrogen atom, a monovalent organic group, or an alkali metal atom. ４ This is a hydrogen atom or a monovalent organic group.

[0045] In equation (1a), R １ ~R ４ The organic group used is not particularly limited, as long as the desired effect is not impaired. １ ~R ４ Examples of organic groups include alkyl groups having 1 to 20 carbon atoms, aliphatic acyl groups having 1 to 20 carbon atoms, and glucopyranosyl groups.

[0046] In equation (1a), R３ Examples of the alkali metal atom include a lithium atom, a sodium atom, a potassium atom, and a strontium atom. Among these, a sodium atom and a potassium atom are preferable, and a sodium atom is more preferable.

[0047] Preferable specific examples of the compound represented by the formula (1a) include ascorbic acid, ascorbyl glucoside, an ester compound formed by condensation of ascorbic acid and a fatty acid, and 3-O-ethyl ascorbic acid. Ascorbic acid is represented by the formula (1a), and R １ ~R ４ is a compound in which is a hydrogen atom. An ester compound formed by condensation of ascorbic acid and a long-chain fatty acid is a compound in which R １ is an acyl group derived from a fatty acid. Specific examples of the ester compound formed by condensation of ascorbic acid and a long-chain fatty acid include ascorbyl palmitate and ascorbyl stearate. Ascorbyl glucoside is represented by the formula (1a). R １ , R ２ , and R ４ are hydrogen atoms. R ３ is a compound in which is an α-D-glucopyranosyl group. 3-O-ethyl ascorbic acid is represented by the formula (1a). R １ , R ２ , and R ４ are hydrogen atoms. R ３ is a compound in which is an ethyl group.

[0048] When the above specific additive contains the compound represented by the formula (1a), ascorbic acid is preferable.

[0049] Phenolic compounds are not particularly limited as long as they are compounds having a phenolic hydroxyl group. Specific examples of phenolic compounds include 2,6-di-tert-butyl-p-cresol (BHT), p-methoxyphenol, 4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole, 2-tert-butyl-4-hydroxyanisole, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol, 4,4'-thiobis(3-methyl-6-tert-butylphenol), tocopherol, and bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid](ethylenebisoxy) One or more substances selected from the group consisting of ethylene (Irganox 245, manufactured by BASF Japan), pentaerythritol tetrakis[3-[3,5-di(tert-butyl)-4-hydroxyphenyl]propionate], bis[3-[3,5-di(tert-butyl)-4-hydroxyphenyl]propionic acid]thiobisethylene, octadecyl-3-(3,5-di-ter-butyl-4-hydroxyphenyl)propionate, octyl-3-(3,5-di-ter-butyl-4-hydroxyphenyl)propionate, 2,4,6-tris(4-hydroxy-3,5-di-tert-butylbenzyl)mesitylene, and 2,4-bis(octylthiomethyl)-6-methylphenol are also included. The tocopherol may be in α, β, γ, or δ form.

[0050] If the above-mentioned specific additive includes a phenolic compound, the phenolic compound is preferably one or more compounds selected from the group consisting of 2,6-di-tert-butyl-p-cresol (BHT), p-methoxyphenol, and tocopherol.

[0051] An unsaturated compound is one or more compounds selected from those represented by the following formula (1b) or formula (1c). ５ -CO-O-CH ２ -CH=C(CH ３ )２ ... (1b) R ６ -O-CHR ７ -CH=C(CH ３ ) ２ ... (1c)

[0052] In equation (1b), R ５ is a monovalent organic group. In formula (1c), R ６ , and R ７ These are each independently monovalent organic groups. ６ and R ７ These elements may be joined together to form a ring.

[0053] R ５ , R ６ , and R ７ The organic group used is not particularly limited, as long as the desired effect is not impaired. ５ , R ６ , and R ７ Examples of organic groups include alkyl groups having 1 to 10 carbon atoms, halogenated alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 10 carbon atoms, halogenated alkenyl groups having 2 to 10 carbon atoms, saturated alicyclic hydrocarbon groups having 3 to 10 carbon atoms, unsaturated alicyclic hydrocarbon groups having 3 to 10 carbon atoms, and aromatic hydrocarbon groups having 6 to 20 carbon atoms.

[0054] Suitable specific examples of the compound represented by formula (1b) include 3-methyl-2-butenyl acetate, 3-methyl-2-butenyl propionate, 3-methyl-2-butenyl butyrate, 3-methyl-2-butenyl valerate, 3-methyl-2-butenyl isovalerate, 3-methyl-2-butenyl pivalate, 3-methyl-2-butenyl monochloroacetate, 3-methyl-2-butenyl dichloroacetate, and 3-methyl-2-butenyl trichloroacetate. Examples include 3-methyl-2-butenyl monobromoacetate, 3-methyl-2-butenyl dibromoacetate, 3-methyl-2-butenyl tribromoacetate, 3-methyl-2-butenyl monofluoroacetate, 3-methyl-2-butenyl difluoroacetate, 3-methyl-2-butenyl trifluoroacetate, 3-methyl-2-butenyl acrylate, 3-methyl-2-butenyl methacrylate, and 3-methyl-2-butenyl benzoate.

[0055] Suitable specific examples of the compound represented by formula (1c) include 2-methyl-4-methoxy-2-pentene, 2-methyl-4-ethoxy-2-pentene, 2-methyl-4-n-propyloxy-2-pentene, 2-methyl-4-isopropyloxy-2-pentene, 1,3-dimethyl-2-butenyl vinyl ether, 2-(2-methyl-1-propenyl)tetrahydrofuran, 2-methyl-5-(2-methyl-1-propenyl)tetrahydrofuran, 2-(2-methyl-1-propenyl)-3,6-dihydro-2H-pyran, 2-(2-methyl-1-propenyl)tetrahydropyran, and 4-methyl-2-(2-methyl-1-propenyl)tetrahydropyran.

[0056] If the above-mentioned specific additive contains an unsaturated compound, 3-methyl-2-butenyl acetate and / or 4-methyl-2-(2-methyl-1-propenyl)tetrahydropyran are preferred as the unsaturated compound.

[0057] The following describes each component that makes up the perovskite solar cell 1.

[0058] The substrate 10 is a structure that supports the other layers and ensures the strength of the perovskite solar cell 1.

[0059] The substrate 10 is usually preferably in the shape of a plate or sheet. The substrate 10 is preferably typically made of metal and / or resin. Alternatively, the substrate 10 may be a silicon semiconductor substrate. In this case, the perovskite solar cell 1 may be a tandem solar cell.

[0060] When the perovskite solar cell 1 receives light from the side of the substrate 10, the substrate 10 is formed from a transparent material. Specifically, if the strength of the solar cell 1 is important, the substrate 10 preferably contains glass. If the lightness and flexibility of the solar cell 1 are important, the substrate 10 is preferably made of resin. As the resin material for the substrate 10, polyimide, polyamide, and polyethylene terephthalate are preferred. From the viewpoint of dimensional stability, polyimide is particularly preferred. If the cost of the product is important, polyethylene terephthalate is particularly preferred. Furthermore, when the perovskite solar cell 1 receives light from the side of the second electrode layer 60, the substrate 10 may be formed from a composite material including a metal layer or the like.

[0061] The first electrode layer 20 collects holes generated in the photoelectric conversion layer 40 through the hole transport layer 30 and outputs them to the outside. The first electrode layer 20 can be formed from a transparent conductive oxide (TCO) that is conductive and light-transmitting. Examples of transparent conductive oxides that can be used to form the first electrode layer 20 include indium oxide, tin oxide, zinc oxide, titanium oxide, and composite oxides thereof. Among these, indium-based composite oxides mainly composed of indium oxide, indium zinc oxide, indium tungsten oxide, indium molybdenum oxide, etc., or fluorine-doped tin oxide are preferred. Indium oxide is particularly preferred from the viewpoint of high conductivity and transparency. To improve the moldability of the hole transport layer 30, the first electrode layer 20 is preferably subjected to a surface treatment such as ozone treatment, and may have a multilayer structure on its surface having a layer of p-type oxide semiconductor mainly composed of, for example, nickel oxide, niobium oxide, etc.

[0062] One example of a method for providing a specific additive between the first electrode layer 20 and the hole transport layer 30 is as follows: First, a solution containing the specific additive is applied or sprayed onto the surface of the first electrode layer 20, and then the solution containing the specific additive adhering to the surface of the first electrode layer 20 is dried to create a layered or scattered presence of the specific additive on the surface of the first electrode layer 20.

[0063] After attaching the specific additive to the surface of the first electrode layer 20 as described above, the hole transport layer 30 is provided on the first electrode layer 20, thereby allowing the specific additive to be present between the first electrode layer 20 and the hole transport layer 30.

[0064] The solvent contained in the solution of the specific additive is not particularly limited as long as the specific additive is dissolved in it. Examples of solvents that dissolve the specific additive include water and solvents described later that may include the liquid composition used to form the hole transport layer 30.

[0065] The hole transport layer 30 effectively transfers holes generated in the photoelectric conversion layer 40 to the first electrode layer 20. Preferably, the hole transport layer 30 is a self-assembled monolayer containing a hole transport material having bonding groups that exert an attractive interaction with the first electrode layer or are capable of forming bonds with the first electrode layer.

[0066] The hole transport material is preferably a compound in which the difference between the HOMO (Highest Occupied Molecular Orbital) of the hole transport material and the VB edge (Valence Band) of the perovskite compound constituting the photoelectric conversion layer 40 is small.

[0067] The above difference is preferably 0.00 to 1.00 eV, more preferably 0.00 to 0.50 eV, and even more preferably 0.00 to 0.30 eV.

[0068] HOMO and LUMO (Lowest Unoccupied Molecular Orbital) can be determined by photoelectron spectroscopy or quantum chemical calculations based on density functional theory.

[0069] As the exchange-correlation functional, B3LYP can be suitably used. For basis functions, 6-311G(d) can be suitably used for optimizing the molecular structure, and 6-311++G(d,p) can be suitably used for calculating the energy.

[0070] As the hole transport material, any compound that has been conventionally used to form the hole transport layer in perovskite solar cells can be used without particular limitation. Preferably, the hole transport material is a compound having an atomic group involved in hole transport and the above-mentioned bonding group.

[0071] Examples of atomic groups involved in hole transport include aromatic compounds containing a triphenylamine skeleton such as Spiro-MeOTAD (CAS number: 207739-72-8), TOP-HTM-α1 (CAS number: 872466-50-7), and TOP-HTM-α2 (CAS number: 2411528-61-3); aromatic compounds containing a carbazole skeleton such as 2PACz (CAS number: 20999-38-6), 4PACz (CAS number: 20999-36-4), MeO-2PACz (CAS number: 2922526-56-3), and Me-2PACz (CAS number: 2747959-96-0); compounds containing a phenothiazine skeleton; compounds containing a thiophene skeleton; and compounds containing a diarylamine skeleton.

[0072] A suitable bonding group is the group represented by the following formula (A): -R １ -R ２ ... (A)

[0073] R １ R is a divalent organic group with 1 to 12 carbon atoms. ２ However, these are phosphonic acid groups, carboxyl groups, sulfonic acid groups, boric acid groups, hydroxyl groups, amino groups, silyl groups, or mercapto groups.

[0074] R １ A divalent organic group may contain heteroatoms in addition to carbon and hydrogen atoms. Examples of heteroatoms include O, N, S, halogen atoms, P, B, and Si.

[0075] R １ The divalent organic group is preferably a hydrocarbon group. The number of carbon atoms in the hydrocarbon group is not particularly limited, but is preferably 1 to 12, and more preferably 1 to 6.

[0076] R １The hydrocarbon group can be an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a combination of an aliphatic hydrocarbon group and an aromatic hydrocarbon group.

[0077] If the hydrocarbon group is an aliphatic hydrocarbon group, the structure of the aliphatic hydrocarbon group may be linear, cyclic, or a combination of linear and cyclic.

[0078] R １ Preferred specific examples of aliphatic hydrocarbon groups include methylene group, ethane-1,2-diyl group (ethylene group), ethane-1,1-diyl group, propane-1,3-diyl group (propylene group), propane-1,2-diyl group (methylethylene group), propane-2,2-diyl group, butane-1,4-diyl group, butane-1,3-diyl group, butane-1,2-diyl group, pentane-1,5-diyl group, and hexane-1,6-diyl group.

[0079] Among these groups, methylene group, ethane-1,2-diyl group (ethylene group), propane-1,3-diyl group (propylene group), butane-1,4-diyl group, and butane-1,3-diyl group (methylpropylene group) are preferred, and ethane-1,2-diyl group (ethylene group), propane-1,3-diyl group (propylene group), and butane-1,3-diyl group (methylpropylene group) are more preferred.

[0080] R １ Preferred specific examples of aromatic hydrocarbon groups include p-phenylene group, m-phenylene group, naphthalene-2,6-diyl group, naphthalene-2,7-diyl group, naphthalene-1,4-diyl group, naphthalene-1,5-diyl group, naphthalene-1,7-diyl group, biphenyl-4,4'-diyl group, biphenyl-3,4'-diyl group, and biphenyl-3,3'-diyl group.

[0081] R ２These are phosphonic acid groups, carboxyl groups, sulfonic acid groups, boric acid groups, hydroxyl groups, amino groups, silyl groups, or mercapto groups. Silyl groups are typically reactive silicon groups that can produce silanol groups by hydrolysis. Such reactive silicon groups have hydrolyzable groups bonded to silicon atoms.

[0082] Specific examples of hydrolyzable groups include halogen atoms, alkoxy groups, acyloxy groups, ketoximate groups, amino groups, amide groups, acid amide groups, aminooxy groups, mercapto groups, and alkenyloxy groups. Among these, alkoxy groups, acyloxy groups, ketoximate groups, and alkenyloxy groups are preferred, and alkoxy groups such as methoxy groups and ethoxy groups are more preferred because they are mildly hydrolyzable and easy to handle.

[0083] Specific examples of reactive silicon groups include dimethoxymethylsilyl group, diethoxymethylsilyl group, trimethoxysilyl group, triethoxysilyl group, dimethoxyphenylsilyl group, methoxymethyldimethoxysilyl group, methoxymethyldiethoxysilyl group, triisopropenyloxysilyl group, and triacetoxysilyl group. Among these, dimethoxymethylsilyl group, trimethoxysilyl group, and methoxymethyldimethoxysilyl group are preferred.

[0084] Since hole transport materials are easy to obtain and prepare, and the hole transport layer 30 is easily formed, in formula (A), R １ However, it is an alkylene group with 1 to 6 carbon atoms, R ２ It is preferable that the group is a phosphonic acid group.

[0085] Suitable specific examples of hole transport materials include N-(2-phosphonoethyl)carbazole (2PACz), N-(2-phosphonoethyl)-3,6-dimethoxycarbazole (MeO-2PACz), N-(2-phosphonoethyl)-3,6-dimethylcarbazole (Me-2PACz), N-(3-phosphonopropyl)carbazole (3PACz), N-(3-phosphonopropyl)-3,6-dimethoxycarbazole (MeO-3PACz), N-(3-phosphonopropyl)-3,6-dimethylcarbazole (Me-3PACz), N-(4-phosphonobutyl)carbazole (4PACz), N-(4-phosphonobutyl)-3,6-dimethoxycarbazole (MeO-4PACz), and N-(4-phosphonobutyl)-3,6-dimethylcarbazole (Me-4PACz).

[0086] Among these, 2PACz, MeO-2PACz, Me-2PACz, MeO-4PACz, and Me-4PACz are more preferred.

[0087] The hole transport layer 30 may contain, in addition to the hole transport material, phosphonic acid compounds such as n-butylphosphonic acid, n-pentylphosphonic acid, n-hexylphosphonic acid, n-octylphosphonic acid, n-decylphosphonic acid, n-octadecylphosphonic acid, 2-ethylhexylphosphonic acid, methoxymethylphosphonic acid, 3-acryloyloxypropylphosphonic acid, 11-hydroxyundecylphosphonic acid, 1H,1H,2H,2H-perfluorophosphonic acid, acetic acid, propionic acid, isobutyric acid, nonanoic acid, fluoroacetic acid, α-chloropropionic acid, and glyoxylic acid. These compounds are not considered hole transport materials. They may be used individually or in combination of two or more.

[0088] The hole transport layer 30 is formed, for example, by coating a liquid composition containing a hole transport material onto the first electrode layer and drying the coated film.

[0089] When the hole transport layer 30 contains the aforementioned specific additive, a liquid composition containing the hole transport material and the specific additive is applied onto the first electrode layer, and the applied film is dried to form the hole transport layer 30.

[0090] If the hole transport layer 30 contains a specific additive, the amount of the specific additive in the hole transport layer 30 is not particularly limited as long as the desired effect is not impaired.

[0091] In terms of achieving both high photoelectric conversion efficiency and durability in the perovskite solar cell 1, the amount of specific additive contained in the hole transport layer 30 is preferably 0.00001% to 95% by mass, more preferably 0.00001% to 50% by mass, and even more preferably 0.0001% to 30% by mass, relative to the mass of the hole transport layer 30.

[0092] The liquid composition used to form the hole transport layer 30 typically contains an organic solvent. Examples of organic solvents include alcohols such as methanol, ethanol, 2-methoxyethanol, isopropanol, and butanol; ethers such as diethyl ether, diisopropyl ether, tetrahydrofuran, 4-methyltetrahydropyran, 2-methyltetrahydrofuran, and cyclopentyl methyl ether; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; amides such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); esters such as ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isoamyl acetate, and γ-butyrolactone (GBL); nitriles such as acetonitrile, propionitrile, and 3-methoxypropionitrile; aromatic compounds such as benzene, toluene, chlorobenzene, and nitrobenzene; chlorinated hydrocarbons such as dichloromethane, chloroform, and 1,2-dichloroethane; and fluorinated hydrocarbons such as chlorofluorocarbons, hydrochlorofluorocarbons, and hydrofluorocarbons. These can be used individually or in combination of two or more.

[0093] The total concentration of the materials constituting the self-assembled monolayer contained in the liquid composition is preferably 0.00001 mg / mL or more and 5.0 mg / mL or less, more preferably 0.00005 mg / mL or more and 4.0 mg / mL or less, and even more preferably 0.0001 mg / mL or more and 3.0 mg / mL or less.

[0094] Furthermore, if the liquid composition contains a specific additive, the content of the specific additive is preferably 0.00001% by mass or more and 95% by mass or less, more preferably 0.00001% by mass or more and 50% by mass or less, and even more preferably 0.0001% by mass or more and 30% by mass or less, relative to the mass of the material constituting the self-assembled monolayer.

[0095] Furthermore, the above liquid composition may also contain a perovskite precursor, described later, which is used to form the photoelectric conversion layer 40. When using a liquid composition containing a perovskite precursor, the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously by coating the liquid composition onto the first electrode layer 20, drying it, and crystallizing the perovskite precursor. In this case, during the process of forming the photoelectric conversion layer 40, compounds such as hole transport materials contained in the liquid composition form a self-assembled monolayer on the first electrode layer 20.

[0096] A liquid composition containing materials constituting a self-assembled monolayer and a perovskite precursor can also contain specific additives.

[0097] When forming a hole transport layer 30 and a photoelectric conversion layer 40 using a liquid composition containing a material constituting a self-assembled monolayer, a perovskite precursor, and a specific additive, the specific additive may be included in both the hole transport layer 30 and the photoelectric conversion layer 40.

[0098] Furthermore, a specific additive may be present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0099] One example of a method for introducing a specific additive between the hole transport layer 30 and the photoelectric conversion layer 40 is as follows: First, a solution containing the specific additive is applied or sprayed onto the surface of the hole transport layer 30. Then, the solution containing the specific additive adhering to the surface of the hole transport layer 30 is dried to create a layered or scattered presence of the specific additive on the surface of the hole transport layer 30. Alternatively, if it is difficult to prepare a solution of the specific additive, the specific additive may be deposited onto the surface of the hole transport layer 30 using various vapor deposition techniques.

[0100] By attaching a specific additive to the surface of the hole transport layer 30 as described above, and then providing the photoelectric conversion layer 40 on top of the hole transport layer 30, the specific additive can be present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0101] The solvent contained in the solution of the specific additive is not particularly limited as long as the specific additive is dissolved in it. Examples of solvents that dissolve the specific additive include water and the aforementioned solvents, which may include the liquid composition used to form the hole transport layer 30.

[0102] Furthermore, it is preferable that a passivation material be present between the hole transport layer 30 and the photoelectric conversion layer 40. The passivation material between the hole transport layer 30 and the photoelectric conversion layer 40 is not shown in Figure 1.

[0103] A specific additive and a passivation material may be present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0104] The passivation material is an organic compound that suppresses defects in the photoelectric conversion layer 40 by interacting with anionic and cationic species on the surface and / or inside the photoelectric conversion layer 40. By passivating the defects in the photoelectric conversion layer 40, the recombination of charge and holes is suppressed, and the photoelectric conversion efficiency is improved.

[0105] The passivation material may exist as a layer of a certain thickness on the surface of the photoelectric conversion layer 40, or it may exist as a single molecule or a composite of multiple molecules inside the photoelectric conversion layer 40 (for example, inside the perovskite crystal bulk or at the grain boundaries).

[0106] The mode of presence of the passivation material in the photoelectric conversion layer 40 may be any of the above modes. In any of the above modes, the photoelectric conversion efficiency of the perovskite solar cell 1 is improved.

[0107] When the passivation material is present as a layer on the surface of the photoelectric conversion layer 40, the surface of the photoelectric conversion layer 40 is passivated by applying the passivation material to the interface between the hole transport layer 30 and the photoelectric conversion layer 40, and / or the interface between the electron transport layer 50 and the photoelectric conversion layer 40.

[0108] In this case, the layer made of passivation material may be present in at least a part of the main surface of the photoelectric conversion layer 40, or it may be present throughout the entire surface, and it is preferable that it is present throughout the entire main surface of the photoelectric conversion layer 40.

[0109] When the passivation material exists inside the photoelectric conversion layer 40 as a single molecule or a composite of multiple molecules, the interaction between the passivation material (as a single molecule or composite of multiple molecules) and the perovskite crystal causes the defects inside the photoelectric conversion layer 40 to be passivated. In this case, typically, the passivation material acts on the crystal lattice of the perovskite compound inside the photoelectric conversion layer 40, causing the grain boundaries and the like to be passivated.

[0110] The passivation material is not particularly limited as long as the desired effect is not impaired. The passivation material can be appropriately selected from various compounds that have been conventionally used as passivation materials in perovskite solar cells. Suitable examples of passivation materials include various amines or their hydrohalides. Examples of hydrohalides include hydrofluoric acid, hydrochloride, hydrobromide, and hydroiodide. Hydrobromide and hydroiodide are preferred among the hydrohalides, and hydroiodide is more preferred.

[0111] Suitable examples of passivation materials include n-butylamine hydrobromide, n-butylamine hydroiodide, n-hexylamine hydrobromide, n-hexylamine hydroiodide, n-decylamine hydrobromide, n-octadecylamine hydroiodide, pyridine hydrobromide, aniline hydroiodide, hydrazine dibromide, ethylenediamine hydroiodide, phenethylamine hydroiodide, 4-fluorinated phenethylamine hydroiodide, phenylenediamine dihydrochloride, diphenylamine hydrobromide, diphenylamine hydroiodide, benzylamine hydroiodide, and 4-diphenylaminophenethylamine hydroiodide.

[0112] Fluorine-containing amine compounds and their salts are also preferred as passivation materials. Preferred specific examples of fluorine-containing amine compounds include, for example, compounds having a fluorinated aromatic group and an amino acid group, such as pentafluorophenylethylalanine hydroiodide, and their salts; fluoroalkylamines such as 6,6,6,5,5,4,4,3,3,2,2-undekafluorohexylamine hydroiodide and 5,5,5,4,4,3,3,2,2-nonafluoropentylamine hydroiodide, and their salts; and compounds having a fluorinated aromatic group and an amino group, such as 4-fluorophenylethylamine hydroiodide, and their salts.

[0113] When a passivation material is present between the hole transport layer 30 and the photoelectric conversion layer 40, a thin film of the passivation material is formed by coating the hole transport layer 30 with a passivation material solution containing the passivation material and an organic solvent, and then drying it. The same solvent used for forming the hole transport layer 30 described above is preferably used as the organic solvent.

[0114] The coating method is not particularly limited. Coating can be performed using, for example, a spin coater, die coater, or bar coater.

[0115] The temperature during application is not particularly limited, but -20°C to 200°C is preferred, and 0°C to 150°C is more preferred.

[0116] The application time is not particularly limited, but 1 second to 24 hours is preferred, and 5 seconds to 1 hour is more preferred.

[0117] Furthermore, by including a passivation material in the liquid composition containing the materials constituting the self-assembled monolayer described above, a layer made of the passivation material can be formed on the surface of the hole transport layer 30.

[0118] The photoelectric conversion layer 40 contains a perovskite compound that performs photoelectric conversion and absorbs incident light to generate photocarriers. The perovskite compound contained in the photoelectric conversion layer 40 is not particularly limited as long as the desired effect is not impaired, and can be appropriately selected from well-known compounds. As a preferred example, the perovskite compound contains an organic atomic group A containing at least one of a monovalent organic ammonium ion and an amidinium-based ion, a metal atom B that generates a divalent metal ion, and a halogen atom X containing at least one of iodide ion I, bromide ion Br, chloride ion Cl, and fluoride ion F, and ABX ３ Compounds represented by can be used. Organic group A is not particularly limited as long as the desired effect is not impaired, and can be appropriately selected from well-known organic compounds. Examples of organic group A include methylammonium MA (CH ３ NH ３ ), formamidinium FA (CH(NH ２ ) ２ (CH ５ N ２ Examples include:

[0119] The metal atom B is not particularly limited as long as it is a metal atom that has been conventionally used in the formation of perovskite compounds. Preferred metal atoms B include lead (Pb) and tin (Sn). When the power generation efficiency of the perovskite solar cell 1 is important, it is preferable that the metal atom B is mainly lead. The lower limit of the lead content in metal atom B is preferably 50% by mass, more preferably 80% by mass, and even more preferably 90% by mass, in order to achieve the desired performance. On the other hand, when the environmental impact of lead is important, it is preferable that the metal atom B is mainly tin (Sn). The lower limit of the tin content in metal atom B is preferably 50% by mass, more preferably 80% by mass, and especially preferably 90% by mass, in order to achieve the desired performance.

[0120] The halogen atom is not particularly limited. At least one of iodide I, bromide Br, and chloride Cl is preferred as the halogen atom X. Furthermore, substituting part or all of the organic atomic group A with alkali metal Am has also been considered, and such perovskite compounds can also be used. The alkali metal Am is not particularly limited. Preferred alkali metal Ams include potassium K, cesium Cs, and rubidium Rb. Among these, cesium Cs and rubidium Rb are preferred as alkali metal Ams when durability and water resistance of the perovskite solar cell 1 are important, and cesium Cs is particularly preferred from the viewpoint of cost and availability.

[0121] Specifically, preferred perovskite compounds include, for example, MAPbI ３ MAPbBr ３ MAPbCl ３ Methylammonium lead halide (MAPbX) ３ ), and FAPbi ３ FAPbBr ３ , and FAPbCl ３ Lead formamidine halogens (FAPbX) ３ ) are examples. Note that halogen atoms X may contain multiple types, and FA may contain both methylammonium and formamidinium as organic atom group A. ｙ MA １－ｙ PbX ３ It may also be included. In addition, if it contains the alkali metal Am, Am ｙ FA ｚ MA １－ｙ－ｚ PbX ３ Am ｙ FA １－ｙ PbX ３ Examples include the following. Am may be a single type of Cs, Rb, or K, or it may contain multiple types (where y and z are real numbers such that 0 ≤ y and z ≤ 1).

[0122] When a passivation material is present between the photoelectric conversion layer 40 and the electron transport layer 50, recombination of photocarriers at the interface between the photoelectric conversion layer 40 and the electron transport layer 50 is prevented, and the arrival of electrons to the electron transport layer 50 is promoted.

[0123] The passivation material placed between the photoelectric conversion layer 40 and the electron transport layer 50 can be the same material as the passivation material placed between the hole transport layer 30 and the photoelectric conversion layer 40.

[0124] As the passivation material to be placed between the photoelectric conversion layer 40 and the electron transport layer 50, the above-mentioned amine hydrohalides, amines having alkyl fluoride, or hydrohalides thereof are preferred.

[0125] As mentioned above, the passivation material can be an amine compound rather than a hydrohalide, but it will still produce the desired effect. In this case, the amine compound interacts with lead ions and other elements that form the perovskite crystal through the lone pair of electrons on the nitrogen atom, thereby preventing charge recombination.

[0126] When a passivation material is present between the photoelectric conversion layer 40 and the electron transport layer 50, it can be formed by coating the photoelectric conversion layer 40 with a passivation material solution containing the passivation material and an organic solvent, and then drying it, similar to the passivation material present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0127] When the perovskite precursor solution used to form the photoelectric conversion layer 40 contains the aforementioned specific additive, the perovskite precursor solution is applied to the hole transport layer 30 and dried, and the perovskite precursor is crystallized, thereby forming a photoelectric conversion layer 40 containing the specific additive in one or more of the surface, polycrystalline interface, and interior.

[0128] When a passivation material is included in the perovskite precursor solution used to form the photoelectric conversion layer 40, the passivation material can be present on the surface and / or inside the photoelectric conversion layer 40 by coating the perovskite precursor solution onto the hole transport layer 30, drying it, and crystallizing the perovskite precursor.

[0129] When the perovskite precursor liquid used to form the photoelectric conversion layer 40 contains a passivation material and a specific additive, the passivation material and the specific additive can be present on the surface and / or inside the photoelectric conversion layer 40 by coating the perovskite precursor liquid onto the hole transport layer 30, drying it, and crystallizing the perovskite precursor.

[0130] Furthermore, the aforementioned liquid composition containing the material constituting the self-assembled monolayer may also contain a perovskite precursor for forming the photoelectric conversion layer 40 and a passivation material. In this case, by coating and drying the liquid composition on the first electrode layer 20 and crystallizing the perovskite precursor, the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously, while the passivation material can be present on the surface and / or inside the photoelectric conversion layer 40.

[0131] Furthermore, the aforementioned liquid composition containing the material constituting the self-assembled monolayer may also contain a perovskite precursor for forming the photoelectric conversion layer 40, a passivation material, and a specific additive. In this case, by coating and drying the liquid composition on the first electrode layer 20 and crystallizing the perovskite precursor, the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously, while the specific additive can be present on the surface and / or inside the hole transport layer 30, and the passivation material and the specific additive can be present on the surface and / or inside the photoelectric conversion layer 40.

[0132] In terms of achieving both high photoelectric conversion efficiency and durability in the perovskite solar cell 1, the amount of specific additive contained in the photoelectric conversion layer 40 is preferably 0.00001% to 95% by mass, more preferably 0.0001% to 50% by mass, and even more preferably 0.0001% to 30% by mass, relative to the mass of the photoelectric conversion layer 40. Furthermore, in the photoelectric conversion layer 40, the ratio of the mass of the specific additive to the mass of the perovskite compound can be arbitrarily adjusted from the viewpoint of balancing power generation performance and durability. For example, the ratio of the mass of the specific additive to the mass of the perovskite compound is preferably 0.0001% to 100% by mass, and more preferably 0.001% to 50% by mass.

[0133] When the perovskite precursor solution contains a passivation material and a perovskite precursor, fluorine-containing amine compounds and their salts are preferred as passivation materials because they are easily precipitated at the interface and surface of the perovskite polycrystal by utilizing the hydrophobic interaction of fluorine atoms. The fluorine content in the fluorine-containing amine compound is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, as the mass of fluorine atoms relative to the molecular weight of each compound. When the fluorine-containing amine compound and its salt contain fluorine atoms in the above ratios, the fluorine-containing amine compound is easily precipitated on the perovskite crystal surface by sufficient hydrophobic interaction.

[0134] A specific additive may be present between the photoelectric conversion layer 40 and the electron transport layer 50.

[0135] One example of a method for providing a specific additive between the photoelectric conversion layer 40 and the electron transport layer 50 is as follows: First, a solution containing the specific additive is applied or sprayed onto the surface of the photoelectric conversion layer 40, and then the solution containing the specific additive adhering to the surface of the photoelectric conversion layer 40 is dried to create a layered or scattered presence of the specific additive on the surface of the photoelectric conversion layer 40. Alternatively, if it is difficult to prepare a solution of the specific additive, the specific additive may be attached to the surface of the photoelectric conversion layer 40 by various vapor deposition techniques.

[0136] By attaching a specific additive to the surface of the photoelectric conversion layer 40 as described above, and then providing an electron transport layer 50 on top of the photoelectric conversion layer 40, the specific additive can be present between the photoelectric conversion layer 40 and the electron transport layer 50.

[0137] The solvent contained in the solution of the specific additive is not particularly limited as long as the specific additive is dissolved in it. Examples of solvents that dissolve the specific additive include water and the aforementioned solvents, which may include the liquid composition used to form the hole transport layer 30.

[0138] The electron transport layer 50 effectively transmits electrons to the second electrode layer 60. The material constituting the electron transport layer 50 is not particularly limited as long as the desired effect is not impaired. The material constituting the electron transport layer 50 can be appropriately selected from various compounds that have been conventionally used to form electron transport layers in perovskite solar cells. The electron transport layer 50 is preferably formed from an electron transport material mainly composed of, for example, fullerene or naphthalene diimide. Examples of fullerenes include C60, C70, their hydrides, oxides, metal complexes, alkyl groups, etc., derivatives to which such as PCBM ([6,6]-Phenyl-C61-Butyric Acid Methyl Ester) can be added. In addition, a hole block layer of bathocuproine (BCP), lithium fluoride (LiF), or magnesium fluoride (MgF) can be placed between the electron transport layer 50 and the second electrode layer 60. ２ ), tin oxide (SnO ２ ), aluminum-doped zinc oxide (ZnO), titanium oxide (TiO ２ ) may contain. The inorganic oxide layer may be doped with another metallic material. The material of the hole block layer is not limited to these.

[0139] When the electron transport layer 50 is formed by coating a liquid composition containing an electron transport material onto the photoelectric conversion layer 40 and then drying the formed coating film, the specific additive can be present on the surface or inside the electron transport layer 50 by including the specific additive together with the electron transport material in the liquid composition.

[0140] In terms of achieving both high photoelectric conversion efficiency and durability in the perovskite solar cell 1, the amount of specific additive contained in the electron transport layer 50 is preferably 0.00001% to 95% by mass, more preferably 0.00001% to 50% by mass, and even more preferably 0.0001% to 30% by mass, relative to the mass of the electron transport layer 50.

[0141] A specific additive may be present between the electron transport layer 50 and the second electrode layer 60.

[0142] One example of a method for providing a specific additive between the electron transport layer 50 and the second electrode layer 60 is as follows: First, a solution containing the specific additive is applied or sprayed onto the surface of the electron transport layer 50, and then the solution containing the specific additive adhering to the surface of the electron transport layer 50 is dried to create a layered or scattered presence of the specific additive on the surface of the electron transport layer 50. Alternatively, if it is difficult to prepare a solution of the specific additive, the specific additive may be attached to the surface of the electron transport layer 50 by various vapor deposition techniques.

[0143] After attaching the specific additive to the surface of the electron transport layer 50 as described above, the second electrode layer 60 is provided on the electron transport layer 50, thereby allowing the specific additive to be present between the electron transport layer 50 and the second electrode layer 60.

[0144] The solvent contained in the solution of the specific additive is not particularly limited as long as the specific additive is dissolved in it. Examples of solvents that dissolve the specific additive include water and the aforementioned solvents, which may include the liquid composition used to form the hole transport layer 30.

[0145] The second electrode layer 60 preferably includes a metal layer, such as copper, to reduce electrical resistance when the perovskite solar cell 1 receives light from the substrate 10 side. However, the metal constituting the metal layer is not limited to copper. Furthermore, when the perovskite solar cell 1 receives light from the second electrode layer 60 side, the second electrode layer 60 may be formed from a transparent conductive oxide.

[0146] A liquid composition comprising (A) lead halide and / or tin halide, (B) formamidine hydrohalide and / or methylamine hydrohalide, (C) organic solvent, and (D) one or more compounds selected from the group consisting of ascorbic acid compounds, phenolic compounds, and unsaturated compounds can be suitably used as a liquid composition for forming the photoelectric conversion layer in a perovskite solar cell.

[0147] (A) Lead halides and / or tin halides, and (B) Formamidine hydrohalides and / or methylamine hydrohalides are so-called perovskite precursors.

[0148] (C) As organic solvents, for example, alcohols such as methanol, ethanol, and 2-methoxyethanol; amide solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); sulfoxides such as dimethyl sulfoxide (DMSO), diethyl sulfoxide, and dibutyl sulfoxide; esters such as ethyl acetate, butyl acetate, propyl acetate, isopropyl acetate, amyl acetate, and γ-butyrolactone (GBL); and aprotic polar solvents such as acetonitrile and propionitrile may be used individually or as a mixture of several types. (C) Organic solvents may also contain other types of organic solvents in addition to the organic solvents mentioned above. The boiling points of these organic solvents are preferably as low as possible because they need to be removed by distillation during the formation of perovskite crystals. Specifically, the boiling points at atmospheric pressure are preferably 300°C or lower, more preferably 200°C or lower, and even more preferably 180°C or lower.

[0149] When using an organic solvent (C) with such a boiling point, the organic solvent (C) is less likely to remain in the perovskite crystal, making it easier to manufacture a perovskite solar cell 1 with the desired performance.

[0150] (D) One or more compounds selected from the group consisting of ascorbic acid compounds, phenolic compounds, and unsaturated compounds are as described above.

[0151] The content of (A) lead halide and / or tin halide in the above liquid composition is preferably 1.0% by mass or more and 99.0% by mass or less, and more preferably 5.0% by mass or more and 90.0% by mass or less, based on the total mass of the liquid composition, in terms of solubility, growth rate of perovskite polycrystals, photoelectric conversion efficiency, and cost.

[0152] The content of (B) formamidine hydrohalide and / or methylamine hydrohalide in the above liquid composition is preferably 0.5 molar equivalents or more and 10 molar equivalents or less, and more preferably 0.8 molar equivalents or more and 5.0 molar equivalents or less, relative to the content (number of moles) of (A) lead halide and / or tin halide.

[0153] The content of one or more compounds selected from the group consisting of (D) ascorbic acid compounds, phenolic compounds, and unsaturated compounds in the above liquid composition is preferably 0.001% to 50% by mass, more preferably 0.005% to 30% by mass, and more preferably 0.01% to 10% by mass, relative to the mass of the liquid composition, from the viewpoint of film formation when the above liquid composition is applied to form a photoelectric conversion layer and from the viewpoint of durability of the perovskite solar cell.

[0154] The above liquid composition may contain one or more selected from the group consisting of (E) cesium halide, (F) passivation material, and (G) hole transport material. (F) passivation material and (G) hole transport material are as described above.

[0155] When the liquid composition contains (E) cesium halide, a perovskite solar cell 1 with excellent durability and water resistance can be easily obtained by forming a photoelectric conversion layer 40 using the liquid composition.

[0156] The advantages of the liquid composition including (F) a passivation material and / or (G) a hole transport material are as described above.

[0157] The content of (E) cesium halide in the above liquid composition is preferably 0 to 10 molar equivalents, and more preferably 0.01 to 5.0 molar equivalents, relative to the content (number of moles) of (A) lead halide and / or tin halide, in terms of the durability of the perovskite solar cell.

[0158] The content of (F) passivation material in the above liquid composition is preferably 0.001% by mass or more and 10% by mass or less, and more preferably 0.01% by mass or more and 5.0% by mass or less, relative to the total mass of (A) lead halide and / or tin halide and (B) formamidine hydrohalide and / or methylamine hydrohalide, in terms of photoelectric conversion efficiency, durability and cost.

[0159] The content of (G) hole transport material in the above liquid composition is preferably 0.001% by mass or more and 10% by mass or less, and more preferably 0.01% by mass or more and 5.0% by mass or less, relative to the total mass of the liquid composition, in terms of photoelectric conversion efficiency, durability, and cost.

[0160] By using the above liquid composition to form the photoelectric conversion layer 40 in the perovskite solar cell 1, a perovskite solar cell with excellent durability can be obtained.

[0161] <<Method for Manufacturing Perovskite Solar Cells>> A perovskite solar cell comprising a first electrode layer 20, a hole transport layer 30, a photoelectric conversion layer 40, an electron transport layer 50, and a second electrode layer 60 in this order can be manufactured by a method that includes forming the photoelectric conversion layer 40 by removing volatile components from a coating film containing a liquid composition containing the above-mentioned components (A) to (D).

[0162] A preferred method for manufacturing a perovskite solar cell 1 is a method comprising: coating a first electrode layer 20 formed on one main surface of a plate-shaped or sheet-shaped substrate 10 with the aforementioned liquid composition to form a hole transport layer 30; forming a photoelectric conversion layer 40 containing a perovskite compound on the hole transport layer 30 by removing volatile components from a coating film containing the liquid composition containing the above components (A) to (D); forming an electron transport layer 50 on the photoelectric conversion layer 40; and forming a second electrode layer 60 on the electron transport layer 50.

[0163] Specifically, the perovskite solar cell 1 can be manufactured by the embodiment of the solar cell manufacturing method shown in Figure 2. The solar cell manufacturing method of this embodiment comprises a first electrode layer formation step (step S11), a hole transport layer formation step (step S12), a precursor liquid coating step (step S13), a crystallization step (step S14), an electron transport layer formation step (step S15), and a second electrode layer formation step (step S16).

[0164] The embodiment of the solar cell manufacturing method shown in Figure 2 may include a first specific additive application step (step S11a, not shown) between the first electrode layer formation step (step S11) and the hole transport layer formation step (step S12), in which a solution containing a specific additive is applied or sprayed onto the surface of the first electrode layer 20, and then the aforementioned solution containing the specific additive that adheres to the surface of the first electrode layer 20 is dried so that the specific additive is present in a layer or scattered on the surface of the first electrode layer 20.

[0165] The embodiment of the solar cell manufacturing method shown in Figure 2 may include a second specific additive application step (step S12a, not shown) between the hole transport layer formation step (step S12) and the precursor liquid coating step (step S13), in which a solution containing a specific additive is applied or sprayed onto the surface of the hole transport layer 30, and the aforementioned solution containing the specific additive adhering to the surface of the hole transport layer 30 is dried to cause the specific additive to be present in a layer or scattered on the surface of the hole transport layer 30.

[0166] The embodiment of the solar cell manufacturing method shown in Figure 2 may include a third specific additive application step (step S14a, not shown) between the crystallization step (step S14) and the electron transport layer formation step (step S15), in which a solution containing a specific additive is applied or sprayed onto the surface of the photoelectric conversion layer 40, and then the aforementioned solution containing the specific additive that adheres to the surface of the photoelectric conversion layer 40 is dried to cause the specific additive to be present in a layer or scattered on the surface of the photoelectric conversion layer 40.

[0167] The embodiment of the solar cell manufacturing method shown in Figure 2 may include a fourth specific additive application step (step S14a, not shown) between the electron transport layer formation step (step S15) and the second electrode layer formation step (step S16), in which a solution containing a specific additive is applied or sprayed onto the surface of the electron transport layer 50, and then the aforementioned solution containing the specific additive that adheres to the surface of the electron transport layer 50 is dried, so that the specific additive is present in a layer or scattered on the surface of the electron transport layer 50.

[0168] The embodiment of the solar cell manufacturing method shown in Figure 2 may include a first passivation material coating step (step S01, not shown in Figure 2) between the hole transport layer formation step (step S12) and the precursor liquid coating step (step S13).

[0169] Furthermore, if a precursor liquid that does not contain passivation material is used in the precursor liquid coating step (step S13), the embodiment of the solar cell manufacturing method shown in Figure 2 may include a second passivation material coating step (step S02, not shown in Figure 2).

[0170] In the hole transport layer formation step (step S12), the electron transport layer formation step (step S15), and the second electrode layer formation step (step S16), the hole transport layer 30 and the electron transport layer 50 containing the specific additive can be formed by the method described above.

[0171] In the first electrode layer formation step S11, a first electrode layer 20 is formed on the main surface of one side of the substrate 10. The first electrode layer 20 can be laminated using a vacuum deposition technique such as sputtering. In addition, in the first electrode layer formation step, it is preferable to modify the surface of the deposited first electrode layer 20 in order to promote the formation of the hole transport layer 30 in the next step. Specific methods for modifying the surface of the first electrode layer 20 include, for example, surface hydroxylation by ultraviolet-ozone treatment or ozonated water washing, deposition of oxides such as nickel oxide using a vacuum deposition technique such as sputtering to facilitate the growth of self-assembled films, deposition of oxide nanoparticles using a coating technique, and heat treatment to activate the surface and remove impurities to facilitate the growth of self-assembled films.

[0172] In step S12, the hole transport layer formation step, the hole transport layer 30 is laminated onto the first electrode layer 20. The hole transport layer 30 can be formed by coating a solution containing the material constituting the hole transport layer 30 and an organic solvent, and then drying. The drying temperature is preferably 50°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher. The drying time is preferably 1 minute or more, more preferably 5 minutes or more, and even more preferably 10 minutes or more. When drying is performed under the above conditions, the organic solvent is sufficiently removed from the coated film, making it easier to obtain the desired crystals in the subsequent step of forming the perovskite polycrystal.

[0173] After forming the hole transport layer 30 in step S12, a first passivation material coating step (step S01) may be performed as needed to coat the hole transport layer 30 with passivation material. In the first passivation material coating step (step S01), a passivation material solution containing passivation material and an organic solvent is coated onto the hole transport layer 30, and then the coated film is dried. In this case, the passivation material can be present on the hole transport layer 30.

[0174] The passivation material solution can be applied using, for example, a spin coater, die coater, and bar coater.

[0175] Furthermore, in step S12, the passivation material can also be present on the hole transport layer 30 by coating it with a liquid composition containing the material constituting the hole transport layer 30 and the passivation material to form the hole transport layer 30.

[0176] In the precursor liquid coating step S13, a liquid composition containing the above components (A) to (D) is coated onto the laminate of the substrate 10, the first electrode layer 20, and the hole transport layer 30 as a perovskite precursor liquid.

[0177] When step S01 is performed, the liquid composition containing components (A) to (D) described above is coated onto the passivation material applied on the hole transport layer 30.

[0178] The liquid composition containing components (A) to (D) can be applied using, for example, a spin coater, die coater, and bar coater.

[0179] A liquid composition containing components (A) to (D) comprises (C) an organic solvent, (A) lead halide and / or tin halide as a perovskite precursor that forms a perovskite compound that performs photoelectric conversion, and (B) formamidine hydrohalide and / or methylamine hydrohalide, and (D) one or more compounds selected from the group consisting of ascorbic acid compounds, phenolic compounds, and unsaturated compounds, which are the aforementioned specific additives. A liquid composition containing components (A) to (D) may also contain perovskite precursors other than components (A) and (B) together with components (A) and (B). Furthermore, a liquid composition containing components (A) to (D) may further contain a hydrogen chloride salt that promotes the growth of crystals of the perovskite compound.

[0180] By using a liquid composition containing components (A) to (D), a photoelectric conversion layer 40 containing component (D), which is the aforementioned specific additive, can be formed in steps S13 and S14.

[0181] The photoelectric conversion layer 40 may be formed using a liquid composition containing (G) a hole transport material and a perovskite precursor as materials constituting the hole transport layer 30. In this case, step S12 for forming the hole transport layer 30 can be omitted. This is because the hole transport layer 30 is formed during the process of forming the photoelectric conversion layer 40 in steps S13 and S14. By using a liquid composition containing (G) a hole transport material and a perovskite precursor, the photoelectric conversion layer 40 containing the aforementioned specific additive component (D) and the hole transport layer 30 containing component (D) can be formed simultaneously in steps S13 and S14.

[0182] A passivation material may be further added to a liquid composition containing (G) a hole transport material, a perovskite precursor, and component (D) as materials constituting the hole transport layer 30. When using a liquid composition containing the materials constituting the hole transport layer 30, a perovskite precursor, and a passivation material, the photoelectric conversion layer 40 can be formed while forming the hole transport layer 30 by steps S13 and S14, and the passivation material and component (D) can be present on the surface and / or inside the photoelectric conversion layer 40.

[0183] The concentration of the liquid composition containing components (A) to (D) is related to the conditions of the crystallization process. The solid content concentration of the liquid composition containing components (A) to (D) is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more.

[0184] When the solid content concentration of the liquid composition containing components (A) to (D) is such that the organic solvent can be volatilized with less energy when forming the photoelectric conversion layer 40, the perovskite solar cell 1 can be manufactured at low cost while reducing the environmental impact.

[0185] Generally, a metal halide BX and a halogenated organic compound AX are used as the perovskite precursor in predetermined proportions, preferably a metal halide BX, a halogenated organic compound AX, and optionally an alkali metal halide AmX are used in predetermined proportions. Lead halide and / or tin halide are preferably used as the metal halide BX. Formamidine hydrohalides and methylamine hydrohalides are preferably used as the halogenated organic compound AX. Cesium halides such as cesium iodide are preferably used as the alkali metal halide AmX. The molar concentration of metal atom B is preferably in excess of 0.5 mol% to 10 mol% relative to the sum of the molar concentration of the organic compound and the molar concentration of alkali metal Am. This allows the perovskite compound ABX to form perovskite crystals in the crystallization process. ３ Components that are not involved in the process are pushed to the front and back interfaces of the perovskite precursor liquid, thereby suppressing the decrease in photoelectric conversion efficiency caused by the retention of other materials within the perovskite crystal. The amounts of (A) lead halide and / or tin halide, and (B) formamidine hydrohalide and / or methylamine hydrohalide used in the liquid composition containing components (A) to (D) are appropriately determined considering the above.

[0186] When the liquid composition containing components (A) to (D) also contains a passivation material, the recombination of photocarriers (holes and electrons) at the interface of the photoelectric conversion layer 40 is suppressed by the action of the passivation material present on and / or inside the photoelectric conversion layer 40.

[0187] Hydrochlorides promote the crystallization of perovskite compounds and increase the grain size of the perovskite crystals. This reduces the area of ​​grain boundaries in the photoelectric conversion layer 40, suppressing the decrease in photoelectric conversion efficiency due to impurities between the perovskite crystals. Examples of hydrochlorides include methylamine hydrochloride (MACl), formamidine hydrochloride (FACl), and methylenediaminium hydrochloride (MDACl). ２) etc. are used. The countercation of the chloride ion of the hydrogen chloride salt is preferably smaller than the crystal lattice of the perovskite crystal and has an amino group. The concentration of the hydrogen chloride salt in the liquid composition containing components (A) to (D) may be 1 mol% to 40 mol% relative to the molar concentration of the metal atom B ion of the perovskite compound.

[0188] In the crystallization step S14, the coating film containing the liquid composition with components (A) to (D) is dried (the solvent is evaporated) to generate crystals of the perovskite compound. This forms a photoelectric conversion layer 40 mainly composed of the perovskite compound.

[0189] When the liquid composition containing components (A) to (D) contains a passivation material, a photoelectric conversion layer 40 is formed, and the passivation material can be present on the surface and / or inside the photoelectric conversion layer 40. As a method to promote the formation of crystals of the perovskite compound in the coating film containing the liquid composition containing components (A) to (D), it is preferable to employ, for example, poor solvent quenching, vacuum quenching, gas quenching, laser treatment, etc. In the crystallization step of step S14, the coating film containing the liquid composition containing components (A) to (D) may be further heated after drying.

[0190] After forming the photoelectric conversion layer 40 in steps S13 and S14, a second passivation material coating step (step S02) may be performed as needed to provide the passivation material on the main surface of the photoelectric conversion layer 40 opposite to the hole transport layer 30. In the second passivation material coating step (step S02), a passivation material solution containing the passivation material and an organic solvent is coated onto the photoelectric conversion layer 40, and then the coating film is dried to provide the passivation material on the photoelectric conversion layer 40.

[0191] In step S15, the electron transport layer formation step, the electron transport layer 50 is formed by methods such as coating or vacuum deposition. A hole block layer may also be formed on the electron transport layer 50 by vacuum deposition or atomic layer deposition.

[0192] In step S16, the second electrode layer formation step, the second electrode layer 60 is formed by methods such as sputtering, vacuum deposition, plating, or coating, depending on the material being formed.

[0193] As described above, perovskite solar cells exhibit high photoelectric conversion efficiency.

[0194] Although embodiments of the present invention A have been described above, the present invention A is not limited to the embodiments described above, and various modifications and variations are possible. The solar cell according to the present invention A may include further functional layers, for example, in a perovskite solar cell, the electron transport layer may be omitted. Furthermore, the perovskite solar cell may be a tandem solar cell using a photoelectric converter such as a crystalline silicon solar cell as a substrate.

[0195] <Embodiment of Invention B>

[0196] Figure 1 is a schematic cross-sectional view showing a preferred configuration of a perovskite solar cell 1 according to an embodiment of the present invention B. The perovskite solar cell 1 comprises a plate-shaped or sheet-shaped substrate 10, a first electrode layer 20 laminated on one main surface of the substrate 10 (the lower side in Figure 1), a hole transport layer 30 laminated on one side of the first electrode layer 20, a photoelectric conversion layer 40 laminated on one side of the hole transport layer 30, an electron transport layer 50 laminated on one side of the photoelectric conversion layer 40, and a second electrode layer 60 (cathode) laminated on one side of the electron transport layer 50.

[0197] A passivation material (not shown) may be present on the surface and / or inside the photoelectric conversion layer 40.

[0198] In the perovskite solar cell 1, one or more oxygen atom-containing compounds selected from succinic acid compounds and phosphorus compounds are included between the first electrode layer 20 and the second electrode layer 60. These compounds share the common characteristic that unpaired electrons in the compound can coordinate to metal ions or lattice defects, or form hydrogen bonds.

[0199] Hereinafter, in the specification of this application, "one or more oxygen atom-containing compounds selected from succinic acid compounds and phosphorus compounds" will also be referred to as "specific additives."

[0200] In other words, in the perovskite solar cell 1, the above-mentioned specific additive is present in at least one of the following locations: inside the hole transport layer 30, inside the photoelectric conversion layer 40, inside the electron transport layer 50, between the first electrode layer 20 and the hole transport layer 30, between the hole transport layer 30 and the photoelectric conversion layer 40, between the photoelectric conversion layer 40 and the electron transport layer 50, and between the electron transport layer 50 and the second electrode layer 60. Of these embodiments, from the viewpoint of the perovskite solar cell having excellent durability, it is preferable that the above-mentioned specific additive is present inside the photoelectric conversion layer 40.

[0201] Succinate compounds are compounds represented by the following formulas (1) to (4).

[0202] In equation (1), R １ , and R ６ Each of these is independently a hydrogen atom, a monovalent organic group, or an alkali metal atom. In formulas (1) to (4), R ２ ~R ５ , R ９ ~R １２ , and R １５ ~R ２２ Each is independently a hydrogen atom or a monovalent organic group. In formula (2), R ７ , R ８ , R １３ , and R １４ Each of these is independently a hydrogen atom or a monovalent organic group. ７ , R ８ , R １３ , and R １４ At least one of them is a monovalent organic group. ７ , R ８ , R １３ , and R １４ It is preferable that all of them are monovalent organic groups. In formula (4), R ２３ This is a hydrogen atom or a monovalent organic group.

[0203] In equations (1) to (4), R １ ~R ２４ The organic group used is not particularly limited, as long as the desired effect is not impaired. １ , R ６ , R ７ , R８ , R １３ , and R ２３ Examples of organic groups include hydrocarbon groups having 1 to 20 carbon atoms. ２ ~R ５ , R ９ ~R １２ , and R １５ ~R ２２ Examples of organic groups include alkyl groups having 1 to 20 carbon atoms.

[0204] In equations (1) to (4), R １ , R ６ , R ７ , R ８ , R １３ , and R ２３ The number of carbon atoms in the hydrocarbon group is preferably 1 to 20, more preferably 1 to 12, even more preferably 1 to 8, and particularly preferably 1 to 4. １ , R ６ , R ７ , R ８ , R １３ , and R ２３ Preferred hydrocarbon groups include alkyl groups, cycloalkyl groups, and aromatic hydrocarbon groups. Preferred examples of alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, and 2-ethylhexyl group. Preferred examples of cycloalkyl groups include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, and cyclooctyl group. Preferred specific examples of aromatic hydrocarbon groups include phenyl group, naphthalene-1-yl group, naphthalene-2-yl group, p-phenylphenyl group, m-phenylphenyl group, and o-phenylphenyl group. In formula (1), R １ , and R ６ Examples of alkali metal atoms include lithium, sodium, potassium, and strontium atoms. Among these, sodium and potassium atoms are preferred, and sodium atoms are more preferred. In formulas (1) to (4), R２ ~R ５ , R ９ ~R １２ , and R １５ ~R ２２ A preferred example of an alkyl group as is R １ , R ６ , R ７ , R ８ , R １３ , and R ２３ Similar to preferred examples of alkyl groups.

[0205] Preferred specific examples of the compound represented by formula (1) include succinic acid; monoalkyl succinates such as methyl succinate, ethyl succinate, n-propyl succinate, isopropyl succinate, and cyclohexyl succinate; and diester succinates such as dimethyl succinate, diethyl succinate, and dicyclohexyl succinate.

[0206] Preferred specific examples of compounds represented by formula (2) include N-alkylsuccinamides such as N-methylsuccinamide, N-ethylsuccinamide, N-n-propylsuccinamide, N-isopropylsuccinamide, N-n-butylsuccinamide, N-isobutylsuccinamide, N-sec-butylsuccinamide, N-tert-butylsuccinamide, N-n-pentylsuccinamide, and N-n-hexylsuccinamide; and N,N'-dimethylsuccinamide. Examples of N,N'-dialkylsuccinamides include N,N'-diethylsuccinamide, N,N'-di-n-propylsuccinamide, N,N'-diisopropylsuccinamide, N,N'-di-n-butylsuccinamide, N,N'-diisobutylsuccinamide, N,N'-di-sec-butylsuccinamide, N,N'-di-tert-butylsuccinamide, N,N'-di-n-pentylsuccinamide, and N,N'-di-n-hexylsuccinamide.

[0207] Suitable examples of compounds represented by formula (3) include succinic anhydride, methyl succinic anhydride, 2,2-dimethyl succinic anhydride, butyl succinic anhydride, isobutyl succinic anhydride, hexyl succinic anhydride, and octyl succinic anhydride.

[0208] Preferred specific examples of compounds represented by formula (4) include succinimides; N-methylsuccinimide, N-ethylsuccinimide, N-n-propylsuccinimide, N-isopropylsuccinimide, N-n-butylsuccinimide, N-isobutylsuccinimide, N-sec-butylsuccinimide, N-tert-butylsuccinimide, N-n-pentylsuccinimide, and N-n-hexylsuccinimide, among other N-alkylsuccinimides.

[0209] When the above-mentioned specific additive contains a succinic acid compound, the succinic acid compound is preferably a dialkyl succinate and / or N-alkylsuccinimide, and more preferably dimethyl succinate and / or N-methylsuccinimide.

[0210] A phosphorus compound is one or more compounds selected from the compounds represented by the following formula (I) or formula (II): O=P(OR １０ ) ３ ...(I), P(OR １１ ) ３ ... (II)

[0211] In equation (I), R １０ Each of these is independently a hydrogen atom, a monovalent organic group, or an alkali metal atom. In formula (II), R １１ Each of these is independently a hydrogen atom, a monovalent organic group, or an alkali metal atom.

[0212] R １０ , and R １１ The organic group used is not particularly limited, as long as the desired effect is not impaired. １０ , and R １１ Examples of organic groups include alkyl groups having 1 to 20 carbon atoms, and aliphatic acyl groups having 1 to 20 carbon atoms.

[0213] Suitable specific examples of compounds represented by formula (I) include phosphoric acid; monoalkyl phosphates such as methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, octyl phosphate, isodecyl phosphate, lauryl phosphate, stearyl phosphate, and isostearyl phosphate; dialkyl phosphates such as dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, diisodecyl phosphate, dilauryl phosphate, distearyl phosphate, and diisostearyl phosphate; and trialkyl phosphates such as trimethyl phosphate, triethyl phosphate, triisodecyl phosphate, trilauryl phosphate, tristearyl phosphate, and triisostearyl phosphate.

[0214] Suitable specific examples of compounds represented by formula (II) include phosphorous acid; monoalkyl phosphorous acid such as methyl phosphate and ethyl phosphate; dialkyl phosphorous acid such as dimethyl phosphate and diethyl phosphate; and trialkyl phosphorous acid such as trimethyl phosphate and triethyl phosphate.

[0215] If the above-mentioned specific additive contains a phosphorus compound, the phosphorus compound is preferably phosphoric acid, phosphorous acid, trialkyl phosphate, and trialkyl phosphate, and more preferably phosphoric acid, trimethyl phosphate, and / or trimethyl phosphate.

[0216] The following describes each component that makes up the perovskite solar cell 1.

[0217] The substrate 10 is a structure that supports the other layers and ensures the strength of the perovskite solar cell 1.

[0218] The substrate 10 is usually preferably in the shape of a plate or sheet. The substrate 10 is preferably typically made of metal and / or resin. Alternatively, the substrate 10 may be a silicon semiconductor substrate. In this case, the perovskite solar cell 1 may be a tandem solar cell.

[0219] When the perovskite solar cell 1 receives light from the side of the substrate 10, the substrate 10 is formed from a transparent material. Specifically, if the strength of the solar cell 1 is important, the substrate 10 preferably contains glass. If the lightness and flexibility of the solar cell 1 are important, the substrate 10 is preferably made of resin. As the resin material for the substrate 10, polyimide, polyamide, and polyethylene terephthalate are preferred. From the viewpoint of dimensional stability, polyimide is particularly preferred. If the cost of the product is important, polyethylene terephthalate is particularly preferred. Furthermore, when the perovskite solar cell 1 receives light from the side of the second electrode layer 60, the substrate 10 may be formed from a composite material including a metal layer or the like.

[0220] The first electrode layer 20 collects holes generated in the photoelectric conversion layer 40 through the hole transport layer 30 and outputs them to the outside. The first electrode layer 20 can be formed from a transparent conductive oxide (TCO) that is conductive and light-transmitting. Examples of transparent conductive oxides that can be used to form the first electrode layer 20 include indium oxide, tin oxide, zinc oxide, titanium oxide, and composite oxides thereof. Among these, indium-based composite oxides mainly composed of indium oxide, indium zinc oxide, indium tungsten oxide, indium molybdenum oxide, etc., or fluorine-doped tin oxide are preferred. Indium oxide is particularly preferred from the viewpoint of high conductivity and transparency. To improve the moldability of the hole transport layer 30, the first electrode layer 20 is preferably subjected to a surface treatment such as ozone treatment, and may have a multilayer structure on its surface having a layer of p-type oxide semiconductor mainly composed of, for example, nickel oxide, niobium oxide, etc.

[0221] One example of a method for providing a specific additive between the first electrode layer 20 and the hole transport layer 30 is as follows: First, a solution containing the specific additive is applied or sprayed onto the surface of the first electrode layer 20, and then the solution containing the specific additive adhering to the surface of the first electrode layer 20 is dried to create a layered or scattered presence of the specific additive on the surface of the first electrode layer 20.

[0222] After attaching the specific additive to the surface of the first electrode layer 20 as described above, the hole transport layer 30 is provided on the first electrode layer 20, thereby allowing the specific additive to be present between the first electrode layer 20 and the hole transport layer 30.

[0223] The solvent contained in the solution of the specific additive is not particularly limited as long as the specific additive is dissolved in it. Examples of solvents that dissolve the specific additive include water and solvents described later that may include the liquid composition used to form the hole transport layer 30.

[0224] The hole transport layer 30 effectively transfers holes generated in the photoelectric conversion layer 40 to the first electrode layer 20. Preferably, the hole transport layer 30 is a self-assembled monolayer containing a hole transport material having bonding groups that exert an attractive interaction with the first electrode layer or are capable of forming bonds with the first electrode layer.

[0225] The hole transport material is preferably a compound in which the difference between the HOMO (Highest Occupied Molecular Orbital) of the hole transport material and the VB edge (Valence Band) of the perovskite compound constituting the photoelectric conversion layer 40 is small.

[0226] The above difference is preferably 0.00 to 1.00 eV, more preferably 0.00 to 0.50 eV, and even more preferably 0.00 to 0.30 eV.

[0227] HOMO and LUMO (lowest unoccupied molecular orbital) can be determined by photoelectron spectroscopy or quantum chemical calculations based on density functional theory.

[0228] As the exchange-correlation functional, B3LYP can be suitably used. For basis functions, 6-311G(d) can be suitably used for optimizing the molecular structure, and 6-311++G(d,p) can be suitably used for calculating the energy.

[0229] As the hole transport material, any compound that has been conventionally used to form the hole transport layer in perovskite solar cells can be used without particular limitation. Preferably, the hole transport material is a compound having an atomic group involved in hole transport and the above-mentioned bonding group.

[0230] Examples of atomic groups involved in hole transport include aromatic compounds containing a triphenylamine skeleton such as Spiro-MeOTAD (CAS number: 207739-72-8), TOP-HTM-α1 (CAS number: 872466-50-7), and TOP-HTM-α2 (CAS number: 2411528-61-3); aromatic compounds containing a carbazole skeleton such as 2PACz (CAS number: 20999-38-6), 4PACz (CAS number: 20999-36-4), MeO-2PACz (CAS number: 2922526-56-3), and Me-2PACz (CAS number: 2747959-96-0); compounds containing a phenothiazine skeleton; compounds containing a thiophene skeleton; and compounds containing a diarylamine skeleton.

[0231] A suitable bonding group is the group represented by the following formula (A): -R １ -R ２ ... (A)

[0232] R １ R is a divalent organic group with 1 to 12 carbon atoms. ２ However, these are phosphonic acid groups, carboxyl groups, sulfonic acid groups, boric acid groups, hydroxyl groups, amino groups, silyl groups, or mercapto groups.

[0233] R １ A divalent organic group may contain heteroatoms in addition to carbon and hydrogen atoms. Examples of heteroatoms include O, N, S, halogen atoms, P, B, and Si.

[0234] R １ The divalent organic group is preferably a hydrocarbon group. The number of carbon atoms in the hydrocarbon group is not particularly limited, but is preferably 1 to 12, and more preferably 1 to 6.

[0235] R １The hydrocarbon group can be an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a combination of an aliphatic hydrocarbon group and an aromatic hydrocarbon group.

[0236] If the hydrocarbon group is an aliphatic hydrocarbon group, the structure of the aliphatic hydrocarbon group may be linear, cyclic, or a combination of linear and cyclic.

[0237] R １ Preferred specific examples of aliphatic hydrocarbon groups include methylene group, ethane-1,2-diyl group (ethylene group), ethane-1,1-diyl group, propane-1,3-diyl group (propylene group), propane-1,2-diyl group (methylethylene group), propane-2,2-diyl group, butane-1,4-diyl group, butane-1,3-diyl group, butane-1,2-diyl group, pentane-1,5-diyl group, and hexane-1,6-diyl group.

[0238] Among these groups, methylene group, ethane-1,2-diyl group (ethylene group), propane-1,3-diyl group (propylene group), butane-1,4-diyl group, and butane-1,3-diyl group (methylpropylene group) are preferred, and ethane-1,2-diyl group (ethylene group), propane-1,3-diyl group (propylene group), and butane-1,3-diyl group (methylpropylene group) are more preferred.

[0239] R １ Preferred specific examples of aromatic hydrocarbon groups include p-phenylene group, m-phenylene group, naphthalene-2,6-diyl group, naphthalene-2,7-diyl group, naphthalene-1,4-diyl group, naphthalene-1,5-diyl group, naphthalene-1,7-diyl group, biphenyl-4,4'-diyl group, biphenyl-3,4'-diyl group, and biphenyl-3,3'-diyl group.

[0240] R ２These are phosphonic acid groups, carboxyl groups, sulfonic acid groups, boric acid groups, hydroxyl groups, amino groups, silyl groups, or mercapto groups. Silyl groups are typically reactive silicon groups that can produce silanol groups by hydrolysis. Such reactive silicon groups have hydrolyzable groups bonded to silicon atoms.

[0241] Specific examples of hydrolyzable groups include halogen atoms, alkoxy groups, acyloxy groups, ketoximate groups, amino groups, amide groups, acid amide groups, aminooxy groups, mercapto groups, and alkenyloxy groups. Among these, alkoxy groups, acyloxy groups, ketoximate groups, and alkenyloxy groups are preferred, and alkoxy groups such as methoxy groups and ethoxy groups are more preferred because they are mildly hydrolyzable and easy to handle.

[0242] Specific examples of reactive silicon groups include dimethoxymethylsilyl group, diethoxymethylsilyl group, trimethoxysilyl group, triethoxysilyl group, dimethoxyphenylsilyl group, methoxymethyldimethoxysilyl group, methoxymethyldiethoxysilyl group, triisopropenyloxysilyl group, and triacetoxysilyl group. Among these, dimethoxymethylsilyl group, trimethoxysilyl group, and methoxymethyldimethoxysilyl group are preferred.

[0243] Since hole transport materials are easy to obtain and prepare, and the hole transport layer 30 is easily formed, in formula (A), R １ However, it is an alkylene group with 1 to 6 carbon atoms, R ２ It is preferable that the group is a phosphonic acid group.

[0244] Suitable specific examples of hole transport materials include N-(2-phosphonoethyl)carbazole (2PACz), N-(2-phosphonoethyl)-3,6-dimethoxycarbazole (MeO-2PACz), N-(2-phosphonoethyl)-3,6-dimethylcarbazole (Me-2PACz), N-(3-phosphonopropyl)carbazole (3PACz), N-(3-phosphonopropyl)-3,6-dimethoxycarbazole (MeO-3PACz), N-(3-phosphonopropyl)-3,6-dimethylcarbazole (Me-3PACz), N-(4-phosphonobutyl)carbazole (4PACz), N-(4-phosphonobutyl)-3,6-dimethoxycarbazole (MeO-4PACz), and N-(4-phosphonobutyl)-3,6-dimethylcarbazole (Me-4PACz).

[0245] Among these, 2PACz, MeO-2PACz, Me-2PACz, MeO-4PACz, and Me-4PACz are more preferred.

[0246] The hole transport layer 30 may contain, in addition to the hole transport material, phosphonic acid compounds such as n-butylphosphonic acid, n-pentylphosphonic acid, n-hexylphosphonic acid, n-octylphosphonic acid, n-decylphosphonic acid, n-octadecylphosphonic acid, 2-ethylhexylphosphonic acid, methoxymethylphosphonic acid, 3-acryloyloxypropylphosphonic acid, 11-hydroxyundecylphosphonic acid, and 1H,1H,2H,2H-perfluorophosphonic acid, as well as other compounds such as acetic acid, propionic acid, isobutyric acid, nonanoic acid, fluoroacetic acid, α-chloropropionic acid, and glyoxylic acid. These compounds do not constitute the hole transport material. They may be used individually or in combination of two or more.

[0247] The hole transport layer 30 is formed, for example, by coating a liquid composition containing a hole transport material onto the first electrode layer and drying the coated film.

[0248] When the hole transport layer 30 contains the aforementioned specific additive, a liquid composition containing the hole transport material and the specific additive is applied onto the first electrode layer, and the applied film is dried to form the hole transport layer 30.

[0249] If the hole transport layer 30 contains a specific additive, the amount of the specific additive in the hole transport layer 30 is not particularly limited as long as the desired effect is not impaired.

[0250] In terms of achieving both high photoelectric conversion efficiency and durability in the perovskite solar cell 1, the amount of specific additive contained in the hole transport layer 30 is preferably 0.00001% to 95% by mass, more preferably 0.00001% to 50% by mass, and even more preferably 0.0001% to 30% by mass, relative to the mass of the hole transport layer 30.

[0251] The liquid composition used to form the hole transport layer 30 typically contains an organic solvent. Examples of organic solvents include alcohols such as methanol, ethanol, 2-methoxyethanol, isopropanol, and butanol; ethers such as diethyl ether, diisopropyl ether, tetrahydrofuran, 4-methyltetrahydropyran, 2-methyltetrahydrofuran, and cyclopentyl methyl ether; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; amides such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); esters such as ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isoamyl acetate, and γ-butyrolactone (GBL); nitriles such as acetonitrile, propionitrile, and 3-methoxypropionitrile; aromatic compounds such as benzene, toluene, chlorobenzene, and nitrobenzene; chlorinated hydrocarbons such as dichloromethane, chloroform, and 1,2-dichloroethane; and fluorinated hydrocarbons such as chlorofluorocarbons, hydrochlorofluorocarbons, and hydrofluorocarbons. These can be used individually or in combination of two or more.

[0252] The total concentration of the materials constituting the self-assembled monolayer contained in the liquid composition is preferably 5.0 mg / mL or less.

[0253] Furthermore, if the liquid composition contains a specific additive, the content of the specific additive is preferably 95% by mass or less, and more preferably 0.00001% by mass or more and 50% by mass or less, relative to the mass of the material constituting the self-assembled monolayer.

[0254] Furthermore, the above liquid composition may also contain a perovskite precursor, described later, which is used to form the photoelectric conversion layer 40. When using a liquid composition containing a perovskite precursor, the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously by coating the liquid composition onto the first electrode layer 20, drying it, and crystallizing the perovskite precursor. In this case, during the process of forming the photoelectric conversion layer 40, compounds such as hole transport materials contained in the liquid composition form a self-assembled monolayer on the first electrode layer 20.

[0255] A liquid composition containing materials constituting a self-assembled monolayer and a perovskite precursor can also contain specific additives.

[0256] When forming a hole transport layer 30 and a photoelectric conversion layer 40 using a liquid composition containing a material constituting a self-assembled monolayer, a perovskite precursor, and a specific additive, the specific additive is included in both the hole transport layer 30 and the photoelectric conversion layer 40.

[0257] Furthermore, a specific additive may be present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0258] One example of a method for introducing a specific additive between the hole transport layer 30 and the photoelectric conversion layer 40 is as follows: First, a solution containing the specific additive is applied or sprayed onto the surface of the hole transport layer 30. Then, the solution containing the specific additive adhering to the surface of the hole transport layer 30 is dried to create a layered or scattered presence of the specific additive on the surface of the hole transport layer 30. Alternatively, if it is difficult to prepare a solution of the specific additive, the specific additive may be deposited onto the surface of the hole transport layer 30 using various vapor deposition techniques.

[0259] By attaching a specific additive to the surface of the hole transport layer 30 as described above, and then providing the photoelectric conversion layer 40 on top of the hole transport layer 30, the specific additive can be present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0260] The solvent contained in the solution of the specific additive is not particularly limited as long as the specific additive is dissolved in it. Examples of solvents that dissolve the specific additive include water and the aforementioned solvents, which may include the liquid composition used to form the hole transport layer 30.

[0261] Furthermore, it is preferable that a passivation material be present between the hole transport layer 30 and the photoelectric conversion layer 40. The passivation material between the hole transport layer 30 and the photoelectric conversion layer 40 is not shown in Figure 1.

[0262] A specific additive and a passivation material may be present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0263] The passivation material is an organic compound that suppresses defects in the photoelectric conversion layer 40 by interacting with anionic and cationic species on the surface and / or inside the photoelectric conversion layer 40. By passivating the defects in the photoelectric conversion layer 40, the recombination of charge and holes is suppressed, and the photoelectric conversion efficiency is improved.

[0264] The passivation material may exist as a layer of a certain thickness on the surface of the photoelectric conversion layer 40, or it may exist as a single molecule or a composite of multiple molecules inside the photoelectric conversion layer 40 (for example, inside the perovskite crystal bulk or at the grain boundaries).

[0265] The mode of presence of the passivation material in the photoelectric conversion layer 40 may be any of the above modes. In any of the above modes, the photoelectric conversion efficiency of the perovskite solar cell 1 is improved.

[0266] When the passivation material is present as a layer on the surface of the photoelectric conversion layer 40, the surface of the photoelectric conversion layer 40 is passivated by applying the passivation material to the interface between the hole transport layer 30 and the photoelectric conversion layer 40, and / or the interface between the electron transport layer 50 and the photoelectric conversion layer 40.

[0267] In this case, the layer made of passivation material may be present in at least a part of the main surface of the photoelectric conversion layer 40, or it may be present throughout the entire surface, and it is preferable that it is present throughout the entire main surface of the photoelectric conversion layer 40.

[0268] When the passivation material exists inside the photoelectric conversion layer 40 as a single molecule or a composite of multiple molecules, the interaction between the passivation material (as a single molecule or composite of multiple molecules) and the perovskite crystal causes the defects inside the photoelectric conversion layer 40 to be passivated. In this case, typically, the passivation material acts on the crystal lattice of the perovskite compound inside the photoelectric conversion layer 40, causing the grain boundaries and the like to be passivated.

[0269] The passivation material is not particularly limited as long as the desired effect is not impaired. The passivation material can be appropriately selected from various compounds that have been conventionally used as passivation materials in perovskite solar cells. Suitable examples of passivation materials include various amines or their hydrohalides. Examples of hydrohalides include hydrofluoric acid, hydrochloride, hydrobromide, and hydroiodide, with hydrobromide and hydroiodide being preferred, and hydroiodide being more preferred.

[0270] Suitable examples of passivation materials include n-butylamine hydrobromide, n-butylamine hydroiodide, n-hexylamine hydrobromide, n-hexylamine hydroiodide, n-decylamine hydrobromide, n-octadecylamine hydroiodide, pyridine hydrobromide, aniline hydroiodide, hydrazine dibromide, ethylenediamine hydroiodide, phenethylamine hydroiodide, 4-fluorinated phenethylamine hydroiodide, phenylenediamine dihydrochloride, diphenylamine hydrobromide, diphenylamine hydroiodide, benzylamine hydroiodide, and 4-diphenylaminophenethylamine hydroiodide.

[0271] Fluorine-containing amine compounds and their salts are also preferred as passivation materials. Preferred specific examples of fluorine-containing amine compounds include, for example, compounds having a fluorinated aromatic group and an amino acid group, such as pentafluorophenylethylalanine hydroiodide, and their salts; fluoroalkylamines such as 6,6,6,5,5,4,4,3,3,2,2-undekafluorohexylamine hydroiodide and 5,5,5,4,4,3,3,2,2-nonafluoropentylamine hydroiodide, and their salts; and compounds having a fluorinated aromatic group and an amino group, such as 4-fluorophenylethylamine hydroiodide, and their salts.

[0272] When a passivation material is present between the hole transport layer 30 and the photoelectric conversion layer 40, a thin film of the passivation material is formed by coating the hole transport layer 30 with a passivation material solution containing the passivation material and an organic solvent, and then drying it. The same solvent used for forming the hole transport layer 30 described above is preferably used as the organic solvent.

[0273] The coating method is not particularly limited. Coating can be performed using, for example, a spin coater, die coater, or bar coater.

[0274] The temperature during application is not particularly limited, but -20°C to 200°C is preferred, and 0°C to 150°C is more preferred.

[0275] The application time is not particularly limited, but 1 second to 24 hours is preferred, and 5 seconds to 1 hour is more preferred.

[0276] Furthermore, by including a passivation material in the liquid composition containing the materials constituting the self-assembled monolayer described above, a layer made of the passivation material can be formed on the surface of the hole transport layer 30.

[0277] The photoelectric conversion layer 40 contains a perovskite compound that performs photoelectric conversion and absorbs incident light to generate photocarriers. The perovskite compound contained in the photoelectric conversion layer 40 is not particularly limited as long as the desired effect is not impaired, and can be appropriately selected from well-known compounds. As a preferred example, the perovskite compound contains an organic atomic group A containing at least one of a monovalent organic ammonium ion and an amidinium-based ion, a metal atom B that generates a divalent metal ion, and a halogen atom X containing at least one of iodide ion I, bromide ion Br, chloride ion Cl, and fluoride ion F, and ABX ３ Compounds represented by can be used. Organic group A is not particularly limited as long as the desired effect is not impaired, and can be appropriately selected from well-known organic compounds. Examples of organic group A include methylammonium MA (CH ３ NH ３ ), formamidinium FA (CH(NH ２ ) ２ (CH ５ N ２ Examples include:

[0278] The metal atom B is not particularly limited as long as it is a metal atom that has been conventionally used in the formation of perovskite compounds. Preferred metal atoms B include lead (Pb) and tin (Sn). When the power generation efficiency of the perovskite solar cell 1 is important, it is preferable that the metal atom B is mainly lead. The lower limit of the lead content in metal atom B is preferably 50% by mass, more preferably 80% by mass, and even more preferably 90% by mass, in order to achieve the desired performance. On the other hand, when the environmental impact of lead is important, it is preferable that the metal atom B is mainly tin (Sn). The lower limit of the tin content in metal atom B is preferably 50% by mass, more preferably 80% by mass, and especially preferably 90% by mass, in order to achieve the desired performance.

[0279] The halogen atom is not particularly limited. At least one of iodide I, bromide Br, and chloride Cl is preferred as the halogen atom X. Furthermore, substituting part or all of the organic atomic group A with alkali metal Am has also been considered, and such perovskite compounds can also be used. The alkali metal Am is not particularly limited. Preferred alkali metal Ams include potassium K, cesium Cs, and rubidium Rb. Among these, cesium Cs and rubidium Rb are preferred as alkali metal Ams when durability and water resistance of the perovskite solar cell 1 are important, and cesium Cs is particularly preferred from the viewpoint of cost and availability.

[0280] Specifically, preferred perovskite compounds include, for example, MAPbI ３ MAPbBr ３ MAPbCl ３ Methylammonium lead halide (MAPbX) ３ ), and FAPbi ３ FAPbBr ３ , and FAPbCl ３ Lead formamidine halogens (FAPbX) ３ ) are examples. Note that halogen atoms X may contain multiple types, and FA may contain both methylammonium and formamidinium as organic atom group A. ｙ MA １－ｙ PbX ３ It may also be included. In addition, if it contains the alkali metal Am, Am ｙ FA ｚ MA １－ｙ－ｚ PbX ３ Am ｙ FA １－ｙ PbX ３ Examples include the following. Am may be a single type of Cs, Rb, or K, or it may contain multiple types (where y and z are real numbers such that 0 ≤ y and z ≤ 1).

[0281] When a passivation material is present between the photoelectric conversion layer 40 and the electron transport layer 50, recombination of photocarriers at the interface between the photoelectric conversion layer 40 and the electron transport layer 50 is prevented, and the arrival of electrons to the electron transport layer 50 is promoted.

[0282] The passivation material placed between the photoelectric conversion layer 40 and the electron transport layer 50 can be the same material as the passivation material placed between the hole transport layer 30 and the photoelectric conversion layer 40.

[0283] As the passivation material to be placed between the photoelectric conversion layer 40 and the electron transport layer 50, the above-mentioned amine hydrohalides, amines having alkyl fluoride, or hydrohalides thereof are preferred.

[0284] As mentioned above, the passivation material can be an amine compound rather than a hydrohalide, but it will still produce the desired effect. In this case, the amine compound interacts with lead ions and other elements that form the perovskite crystal through the lone pair of electrons on the nitrogen atom, thereby preventing charge recombination.

[0285] When a passivation material is present between the photoelectric conversion layer 40 and the electron transport layer 50, it can be formed by coating the photoelectric conversion layer 40 with a passivation material solution containing the passivation material and an organic solvent, and then drying it, similar to the passivation material present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0286] When the perovskite precursor solution used to form the photoelectric conversion layer 40 contains the aforementioned specific additive, the perovskite precursor solution is applied to the hole transport layer 30 and dried, and the perovskite precursor is crystallized, thereby forming a photoelectric conversion layer 40 containing the specific additive in one or more of the surface, polycrystalline interface, and interior.

[0287] When a passivation material is included in the perovskite precursor solution used to form the photoelectric conversion layer 40, the passivation material can be present on the surface and / or inside the photoelectric conversion layer 40 by coating the perovskite precursor solution onto the hole transport layer 30, drying it, and crystallizing the perovskite precursor.

[0288] When a passivation material and a specific additive are contained in the perovskite precursor liquid used to form the photoelectric conversion layer 40, the perovskite precursor liquid is applied and dried on the hole transport layer 30, and the perovskite precursor is crystallized, so that the passivation material and the specific additive can be present on the surface and / or inside of the photoelectric conversion layer 40.

[0289] Further, the above liquid composition containing the material constituting the self-assembled monolayer may contain a perovskite precursor for forming the photoelectric conversion layer 40 and a passivation material. In this case, the liquid composition is applied and dried on the first electrode layer 20, and the perovskite precursor is crystallized, so that the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously, and the passivation material can be present on the surface and / or inside of the photoelectric conversion layer 40.

[0290] Furthermore, the above liquid composition containing the material constituting the self-assembled monolayer may contain a perovskite precursor for forming the photoelectric conversion layer 40, a passivation material, and a specific additive. In this case, the liquid composition is applied and dried on the first electrode layer 20, and the perovskite precursor is crystallized, so that the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously, and the specific additive can be present on the surface and / or inside of the hole transport layer, and the passivation material and the specific additive can be present on the surface and / or inside of the photoelectric conversion layer 40.

[0291] In terms of achieving both high photoelectric conversion efficiency and durability in the perovskite solar cell 1, the amount of the specific additive contained in the photoelectric conversion layer 40 is preferably 0.00001% by mass or more and 95% by mass or less, more preferably 0.0001% by mass or more and 50% by mass or less, and even more preferably 0.0001% by mass or more and 30% by mass or less, based on the mass of the photoelectric conversion layer 40. Further, in the photoelectric conversion layer 40, the ratio of the mass of the specific additive to the mass of the perovskite compound can be arbitrarily adjusted from the viewpoint of the balance between power generation performance and durability. The ratio of the mass of the specific additive to the mass of the perovskite compound is preferably, for example, 0.0001% by mass or more and 100% by mass or less, and more preferably 0.001% by mass or more and 50% by mass or less.

[0292] When the perovskite precursor liquid contains a passivation material and a perovskite precursor, fluorine-containing amine compounds and their salts are preferable as the passivation material in terms of being easily deposited on the interfaces and surfaces of perovskite polycrystals by utilizing hydrophobic interactions by fluorine atoms. The content of fluorine atoms in the fluorine-containing amine compound is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, as the mass of fluorine atoms in the molecular weight of each compound. When the fluorine-containing amine compound and its salt contain fluorine atoms in the above ratio, the fluorine-containing amine compound is easily deposited on the perovskite crystal surface due to sufficient hydrophobic interactions.

[0293] A specific additive may be present between the photoelectric conversion layer 40 and the electron transport layer 50.

[0294] Examples of the method of making the specific additive present between the photoelectric conversion layer 40 and the electron transport layer 50 include the following methods. First, after applying or spraying a solution containing the specific additive on the surface of the photoelectric conversion layer 40, the solution containing the above-mentioned specific additive adhering to the surface of the photoelectric conversion layer 40 is dried to make the specific additive present in a layer or in spots on the surface of the photoelectric conversion layer 40. Also, when it is difficult to prepare a solution of the specific additive, the specific additive may be adhered to the surface of the photoelectric conversion layer 40 by various vapor deposition techniques.

[0295] By attaching a specific additive to the surface of the photoelectric conversion layer 40 as described above, and then providing an electron transport layer 50 on top of the photoelectric conversion layer 40, the specific additive can be present between the photoelectric conversion layer 40 and the electron transport layer 50.

[0296] The solvent contained in the solution of the specific additive is not particularly limited as long as the specific additive is dissolved in it. Examples of solvents that dissolve the specific additive include water and the aforementioned solvents, which may include the liquid composition used to form the hole transport layer 30.

[0297] The electron transport layer 50 effectively transmits electrons to the second electrode layer 60. The material constituting the electron transport layer 50 is not particularly limited as long as the desired effect is not impaired. The material constituting the electron transport layer 50 can be appropriately selected from various compounds that have been conventionally used to form electron transport layers in perovskite solar cells. The electron transport layer 50 is preferably formed from an electron transport material mainly composed of, for example, fullerene or naphthalene diimide. Examples of fullerenes include C60, C70, their hydrides, oxides, metal complexes, alkyl groups, etc., derivatives to which such as PCBM ([6,6]-Phenyl-C61-Butyric Acid Methyl Ester) can be added. In addition, a hole block layer of bathocuproine (BCP), lithium fluoride (LiF), or magnesium fluoride (MgF) can be placed between the electron transport layer 50 and the second electrode layer 60. ２ ), tin oxide (SnO ２ ), aluminum-doped zinc oxide (ZnO), titanium oxide (TiO ２ ) may contain. The inorganic oxide layer may be doped with another metallic material. The material of the hole block layer is not limited to these.

[0298] When the electron transport layer 50 is formed by coating a liquid composition containing an electron transport material onto the photoelectric conversion layer 40 and then drying the formed coating film, the specific additive can be present on the surface or inside the electron transport layer 50 by including the specific additive together with the electron transport material in the liquid composition.

[0299] In terms of achieving both high photoelectric conversion efficiency and durability in the perovskite solar cell 1, the amount of specific additive contained in the electron transport layer 50 is preferably 0.00001% to 95% by mass, more preferably 0.00001% to 50% by mass, and even more preferably 0.0001% to 30% by mass, relative to the mass of the electron transport layer 50.

[0300] A specific additive may be present between the electron transport layer 50 and the second electrode layer 60.

[0301] One example of a method for providing a specific additive between the electron transport layer 50 and the second electrode layer 60 is as follows: First, a solution containing the specific additive is applied or sprayed onto the surface of the electron transport layer 50, and then the solution containing the specific additive adhering to the surface of the electron transport layer 50 is dried to create a layered or scattered presence of the specific additive on the surface of the electron transport layer 50. Alternatively, if it is difficult to prepare a solution of the specific additive, the specific additive may be attached to the surface of the electron transport layer 50 by various vapor deposition techniques.

[0302] After attaching the specific additive to the surface of the electron transport layer 50 as described above, the second electrode layer 60 is provided on the electron transport layer 50, thereby allowing the specific additive to be present between the electron transport layer 50 and the second electrode layer 60.

[0303] The solvent contained in the solution of the specific additive is not particularly limited as long as the specific additive is dissolved in it. Examples of solvents that dissolve the specific additive include water and the aforementioned solvents, which may include the liquid composition used to form the hole transport layer 30.

[0304] The second electrode layer 60 preferably includes a metal layer, such as copper, to reduce electrical resistance when the perovskite solar cell 1 receives light from the substrate 10 side. However, the metal constituting the metal layer is not limited to copper. Furthermore, when the perovskite solar cell 1 receives light from the second electrode layer 60 side, the second electrode layer 60 may be formed from a transparent conductive oxide.

[0305] A liquid composition comprising (A) lead halide and / or tin halide, (B) formamidine hydrohalide and / or methylamine hydrohalide, (C) organic solvent, and (D) oxygen atom-containing compound, wherein (D) oxygen atom-containing compound is one or more selected from succinic acid compounds and phosphorus compounds, can be suitably used as a liquid composition for forming a photoelectric conversion layer in a perovskite solar cell.

[0306] (A) Lead halides and / or tin halides, and (B) Formamidine hydrohalides and / or methylamine hydrohalides are so-called perovskite precursors.

[0307] (C) As organic solvents, for example, alcohols such as methanol, ethanol, and 2-methoxyethanol; amide solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); sulfoxides such as dimethyl sulfoxide (DMSO), diethyl sulfoxide, and dibutyl sulfoxide; esters such as ethyl acetate, butyl acetate, propyl acetate, isopropyl acetate, amyl acetate, and γ-butyrolactone (GBL); and aprotic polar solvents such as acetonitrile and propionitrile may be used individually or as a mixture of several types. (C) Organic solvents may also contain other types of organic solvents in addition to the organic solvents mentioned above. The boiling points of these organic solvents are preferably as low as possible because they need to be removed by distillation during the formation of perovskite crystals. Specifically, the boiling points at atmospheric pressure are preferably 300°C or lower, more preferably 200°C or lower, and even more preferably 180°C or lower.

[0308] When using an organic solvent (C) with such a boiling point, the organic solvent (C) is less likely to remain in the perovskite crystal, making it easier to manufacture a perovskite solar cell 1 with the desired performance.

[0309] (D) The oxygen atom-containing compounds, one or more compounds selected from succinic acid compounds and phosphorus compounds, are as described above.

[0310] The content of (A) lead halide and / or tin halide in the above liquid composition is preferably 1.0% by mass or more and 99.0% by mass or less, and more preferably 5.0% by mass or more and 90.0% by mass or less, based on the total mass of the liquid composition, in terms of solubility, growth rate of perovskite polycrystals, photoelectric conversion efficiency, and cost.

[0311] The content of (B) formamidine hydrohalide and / or methylamine hydrohalide in the above liquid composition is preferably 0.5 molar equivalents or more and 10 molar equivalents or less, and more preferably 0.8 molar equivalents or more and 5.0 molar equivalents or less, relative to the content (number of moles) of (A) lead halide and / or tin halide.

[0312] In the above liquid composition, the content of (D) oxygen atom-containing compound is preferably 0.001% to 50% by mass, more preferably 0.005% to 30% by mass, and more preferably 0.01% to 10% by mass, relative to the mass of the liquid composition, from the viewpoint of film formation when the above liquid composition is applied to form a photoelectric conversion layer and from the viewpoint of durability of the perovskite solar cell.

[0313] The above liquid composition may contain one or more selected from the group consisting of (E) cesium halide, (F) passivation material, and (G) hole transport material. (F) passivation material and (G) hole transport material are as described above.

[0314] When the liquid composition contains (E) cesium halide, a perovskite solar cell 1 with excellent durability and water resistance can be easily obtained by forming a photoelectric conversion layer 40 using the liquid composition.

[0315] The advantages of the liquid composition including (F) a passivation material and / or (G) a hole transport material are as described above.

[0316] The content of (E) cesium halide in the above liquid composition is preferably 0 to 10 molar equivalents, and more preferably 0.01 to 5.0 molar equivalents, relative to the content (number of moles) of (A) lead halide and / or tin halide, in terms of the durability of the perovskite solar cell.

[0317] The content of (F) passivation material in the above liquid composition is preferably 0.001% by mass or more and 10% by mass or less, and more preferably 0.01% by mass or more and 5.0% by mass or less, relative to the total mass of (A) lead halide and / or tin halide and (B) formamidine hydrohalide and / or methylamine hydrohalide, in terms of photoelectric conversion efficiency, durability and cost.

[0318] The content of (G) hole transport material in the above liquid composition is preferably 0.001% by mass or more and 10% by mass or less, and more preferably 0.01% by mass or more and 5.0% by mass or less, relative to the total mass of the liquid composition, in terms of photoelectric conversion efficiency, durability, and cost.

[0319] By using the above liquid composition to form the photoelectric conversion layer 40 in the perovskite solar cell 1, a perovskite solar cell with excellent durability can be obtained.

[0320] <<Method for Manufacturing Perovskite Solar Cells>> A perovskite solar cell comprising a first electrode layer 20, a hole transport layer 30, a photoelectric conversion layer 40, an electron transport layer 50, and a second electrode layer 60 in this order can be manufactured by a method that includes forming the photoelectric conversion layer 40 by removing volatile components from a coating film containing a liquid composition containing the above-mentioned components (A) to (D).

[0321] A preferred method for manufacturing the perovskite solar cell 1 includes coating the above-described liquid composition on a first electrode layer 20 formed on one main surface of a plate-like or sheet-like substrate 10 to form a hole transport layer 30, and removing volatile components from a coating film containing the liquid composition containing the above components (A) to (D) on the hole transport layer 30 to form a photoelectric conversion layer 40 containing a perovskite compound, forming an electron transport layer 50 on the photoelectric conversion layer 40, and forming a second electrode layer 60 on the electron transport layer 50.

[0322] Specifically, the perovskite solar cell 1 can be manufactured by the embodiment of the solar cell manufacturing method shown in FIG. 2. The solar cell manufacturing method of this embodiment includes a first electrode layer forming step (step S11), a hole transport layer forming step (step S12), a precursor liquid coating step (step S13), a crystallization step (step S14), an electron transport layer forming step (step S15), and a second electrode layer forming step (step S16).

[0323] The embodiment of the solar cell manufacturing method shown in FIG. 2 may include a first specific additive imparting step (steps S11a, not shown) in which a solution containing a specific additive is applied or sprayed onto the surface of the first electrode layer 20 and then the solution containing the above-described specific additive adhering to the surface of the first electrode layer 20 is dried so that the specific additive is present in a layer or in dots on the surface of the first electrode layer 20, between the first electrode layer forming step (step S11) and the hole transport layer forming step (step S12).

[0324] The embodiment of the solar cell manufacturing method shown in FIG. 2 may include a second specific additive imparting step (steps S12a, not shown) in which a solution containing a specific additive is applied or sprayed onto the surface of the hole transport layer 30 and then the solution containing the above-described specific additive adhering to the surface of the hole transport layer 30 is dried so that the specific additive is present in a layer or in dots on the surface of the hole transport layer 30, between the hole transport layer forming step (step S12) and the precursor liquid coating step (step S13).

[0325] The embodiment of the solar cell manufacturing method shown in Figure 2 may include a third specific additive application step (step S14a, not shown) between the crystallization step (step S14) and the electron transport layer formation step (step S15), in which a solution containing a specific additive is applied or sprayed onto the surface of the photoelectric conversion layer 40, and then the aforementioned solution containing the specific additive that adheres to the surface of the photoelectric conversion layer 40 is dried to cause the specific additive to be present in a layer or scattered on the surface of the photoelectric conversion layer 40.

[0326] The embodiment of the solar cell manufacturing method shown in Figure 2 may include a fourth specific additive application step (step S14a, not shown) between the electron transport layer formation step (step S15) and the second electrode layer formation step (step S16), in which a solution containing a specific additive is applied or sprayed onto the surface of the electron transport layer 50, and then the aforementioned solution containing the specific additive that adheres to the surface of the electron transport layer 50 is dried, so that the specific additive is present in a layer or scattered on the surface of the electron transport layer 50.

[0327] The embodiment of the solar cell manufacturing method shown in Figure 2 may include a first passivation material coating step (step S01, not shown in Figure 2) between the hole transport layer formation step (step S12) and the precursor liquid coating step (step S13).

[0328] Furthermore, if a precursor liquid that does not contain passivation material is used in the precursor liquid coating step (step S13), the embodiment of the solar cell manufacturing method shown in Figure 2 may include a second passivation material coating step (step S02, not shown in Figure 2).

[0329] In the hole transport layer formation step (step S12), the electron transport layer formation step (step S15), and the second electrode layer formation step (step S16), the hole transport layer 30 and the electron transport layer 50 containing the specific additive can be formed by the method described above.

[0330] In the first electrode layer formation step S11, a first electrode layer 20 is formed on the main surface of one side of the substrate 10. The first electrode layer 20 can be laminated using a vacuum deposition technique such as sputtering. In addition, in the first electrode layer formation step, it is preferable to modify the surface of the deposited first electrode layer 20 in order to promote the formation of the hole transport layer 30 in the next step. Specific methods for modifying the surface of the first electrode layer 20 include, for example, surface hydroxylation by ultraviolet-ozone treatment or ozonated water washing, deposition of oxides such as nickel oxide that facilitate the growth of self-assembled films using a vacuum deposition technique such as sputtering, deposition of oxide nanoparticles using a coating technique, and heat treatment to activate the surface and remove impurities so that self-assembled films can grow easily.

[0331] In step S12, the hole transport layer formation step, the hole transport layer 30 is laminated onto the first electrode layer 20. The hole transport layer 30 can be formed by coating a solution containing the material constituting the hole transport layer 30 and an organic solvent, and then drying. The drying temperature is preferably 50°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher. The drying time is preferably 1 minute or more, more preferably 5 minutes or more, and even more preferably 10 minutes or more. When drying is performed under the above conditions, the organic solvent is sufficiently removed from the coated film, making it easier to obtain the desired crystals in the subsequent step of forming the perovskite polycrystal.

[0332] After forming the hole transport layer 30 in step S12, a first passivation material coating step (step S01) may be performed as needed to coat the hole transport layer 30 with passivation material. In the first passivation material coating step (step S01), a passivation material solution containing passivation material and an organic solvent is coated onto the hole transport layer 30, and then the coated film is dried. In this case, the passivation material can be present on the hole transport layer 30.

[0333] The passivation material solution can be applied using, for example, a spin coater, die coater, and bar coater.

[0334] Furthermore, in step S12, the passivation material can also be present on the hole transport layer 30 by coating it with a liquid composition containing the material constituting the hole transport layer 30 and the passivation material to form the hole transport layer 30.

[0335] In the precursor liquid coating step S13, a liquid composition containing the above components (A) to (D) is coated onto the laminate of the substrate 10, the first electrode layer 20, and the hole transport layer 30 as a perovskite precursor liquid.

[0336] When step S01 is performed, the liquid composition containing components (A) to (D) described above is coated onto the passivation material applied on the hole transport layer 30.

[0337] The liquid composition containing components (A) to (D) can be applied using, for example, a spin coater, die coater, and bar coater.

[0338] A liquid composition containing components (A) to (D) comprises (C) an organic solvent, (A) lead halide and / or tin halide as perovskite precursors that form a perovskite compound that performs photoelectric conversion, and (B) formamidine hydrohalide and / or methylamine hydrohalide, and (D) an oxygen atom-containing compound, which is the aforementioned specific additive. A liquid composition containing components (A) to (D) may also contain perovskite precursors other than components (A) and (B) along with components (A) and (B). Furthermore, a liquid composition containing components (A) to (D) may further contain a hydrogen chloride salt that promotes the growth of crystals of the perovskite compound.

[0339] By using a liquid composition containing components (A) to (D), a photoelectric conversion layer 40 containing component (D), which is the aforementioned specific additive, can be formed in steps S13 and S14.

[0340] The photoelectric conversion layer 40 may be formed using a liquid composition containing (G) a hole transport material and a perovskite precursor as materials constituting the hole transport layer 30. In this case, step S12 for forming the hole transport layer 30 can be omitted. This is because the hole transport layer 30 is formed during the process of forming the photoelectric conversion layer 40 in steps S13 and S14. By using a liquid composition containing (G) a hole transport material and a perovskite precursor, the photoelectric conversion layer 40 containing the aforementioned specific additive component (D) and the hole transport layer 30 containing component (D) can be formed simultaneously in steps S13 and S14.

[0341] A passivation material may be further added to a liquid composition containing (G) a hole transport material, a perovskite precursor, and component (D) as materials constituting the hole transport layer 30. When using a liquid composition containing the materials constituting the hole transport layer 30, a perovskite precursor, and a passivation material, the photoelectric conversion layer 40 can be formed while forming the hole transport layer 30 by steps S13 and S14, and the passivation material and component (D) can be present on the surface and / or inside the photoelectric conversion layer 40.

[0342] The concentration of the liquid composition containing components (A) to (D) is related to the conditions of the crystallization process. The solid content concentration of the liquid composition containing components (A) to (D) is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more.

[0343] When the solid content concentration of the liquid composition containing components (A) to (D) is such that the organic solvent can be volatilized with less energy when forming the photoelectric conversion layer 40, the perovskite solar cell 1 can be manufactured at low cost while reducing the environmental impact.

[0344] Generally, a metal halide BX and a halogenated organic compound AX are used as the perovskite precursor in predetermined proportions, preferably a metal halide BX, a halogenated organic compound AX, and, if necessary, an alkali metal halide AmX are used in predetermined proportions. As the metal halide BX, lead halide and / or tin halide are preferably used. As the halogenated organic compound AX, formamidine hydrohalides and methylamine hydrohalides are preferably used. As the alkali metal halide AmX, cesium halides such as cesium iodide are preferably used. The molar concentration of metal atom B is preferably in excess of 0.5 mol% to 10 mol% relative to the sum of the molar concentration of the organic compound and the molar concentration of alkali metal Am. This makes it possible to expel other materials to the front and back interfaces of the perovskite precursor solution during the crystallization process, and to suppress the decrease in photoelectric conversion efficiency caused by the retention of other materials in the perovskite crystal. The amounts used in a liquid composition containing components (A) to (D), namely (A) lead halide and / or tin halide, and (B) formamidine hydrohalide and / or methylamine hydrohalide, are determined appropriately considering the above.

[0345] When the liquid composition containing components (A) to (D) also contains a passivation material, the recombination of photocarriers (holes and electrons) at the interface of the photoelectric conversion layer 40 is suppressed by the action of the passivation material present on and / or inside the photoelectric conversion layer 40.

[0346] Hydrochlorides promote the crystallization of perovskite compounds and increase the grain size of the perovskite crystals. This reduces the area of ​​grain boundaries in the photoelectric conversion layer 40, suppressing the decrease in photoelectric conversion efficiency due to impurities between the perovskite crystals. Examples of hydrochlorides include methylamine hydrochloride (MACl), formamidine hydrochloride (FACl), and methylenediaminium hydrochloride (MDACl). ２) etc. are used. The portion other than the hydrogen chloride is preferably smaller than or equal to the crystal lattice of the perovskite crystal and has an amino group. The concentration of the hydrogen chloride in the liquid composition containing components (A) to (D) may be 1 mol% to 40 mol% with respect to the molar concentration of the metal atom B ion of the perovskite compound.

[0347] In the crystallization step S14, the coating film containing the liquid composition with components (A) to (D) is dried (the solvent is evaporated) to generate crystals of the perovskite compound. This forms a photoelectric conversion layer 40 mainly composed of the perovskite compound.

[0348] When the liquid composition containing components (A) to (D) contains a passivation material, a photoelectric conversion layer 40 is formed, and the passivation material can be present on the surface and / or inside the photoelectric conversion layer 40. As a method to promote the formation of crystals of the perovskite compound in the coating film containing the liquid composition containing components (A) to (D), it is preferable to employ, for example, poor solvent quenching, vacuum quenching, gas quenching, laser treatment, etc. In the crystallization step of step S14, the coating film containing the liquid composition containing components (A) to (D) may be further heated after drying.

[0349] After forming the photoelectric conversion layer 40 in steps S13 and S14, a second passivation material coating step (step S02) may be performed as needed to provide the passivation material on the main surface of the photoelectric conversion layer 40 opposite to the hole transport layer 30. In the second passivation material coating step (step S02), a passivation material solution containing the passivation material and an organic solvent is coated onto the photoelectric conversion layer 40, and then the coating film is dried to provide the passivation material on the photoelectric conversion layer 40.

[0350] In step S15, the electron transport layer formation step, the electron transport layer 50 is formed by methods such as coating or vacuum deposition. A hole block layer may also be formed on the electron transport layer 50 by vacuum deposition or atomic layer deposition.

[0351] In step S16, the second electrode layer formation step, the second electrode layer 60 is formed by methods such as sputtering, vacuum deposition, plating, or coating, depending on the material being formed.

[0352] As described above, perovskite solar cells exhibit high photoelectric conversion efficiency.

[0353] Although embodiments of the present invention B have been described above, the present invention B is not limited to the embodiments described above, and various modifications and variations are possible. The solar cell according to the present invention B may have further functional layers, for example, in a perovskite solar cell, the electron transport layer may be omitted. Furthermore, the perovskite solar cell may be a tandem solar cell using a photoelectric converter such as a crystalline silicon solar cell as a substrate.

[0354] <Embodiment of Invention C> Figure 1 is a schematic cross-sectional view showing a preferred configuration of a perovskite solar cell 1 according to an embodiment of Invention C. The perovskite solar cell 1 comprises a plate-shaped or sheet-shaped substrate 10, a first electrode layer 20 laminated on one main surface of the substrate 10 (the lower side in Figure 1), a hole transport layer 30 laminated on one side of the first electrode layer 20, a photoelectric conversion layer 40 laminated on one side of the hole transport layer 30, an electron transport layer 50 laminated on one side of the photoelectric conversion layer 40, and a second electrode layer 60 (cathode) laminated on one side of the electron transport layer 50.

[0355] A passivation material (not shown) may be present on the surface and / or inside the photoelectric conversion layer 40.

[0356] In the perovskite solar cell 1, phosphorus pentoxide is contained between the first electrode layer 20 and the second electrode layer 60. Phosphorus pentoxide is a colorless solid at room temperature.

[0357] In other words, in the perovskite solar cell 1, phosphorus pentoxide is present in at least one of the following locations: inside the hole transport layer 30, inside the photoelectric conversion layer 40, inside the electron transport layer 50, between the first electrode layer 20 and the hole transport layer 30, between the hole transport layer 30 and the photoelectric conversion layer 40, between the photoelectric conversion layer 40 and the electron transport layer 50, and between the electron transport layer 50 and the second electrode layer 60.

[0358] The following describes each component that makes up the perovskite solar cell 1.

[0359] The substrate 10 is a structure that supports the other layers and ensures the strength of the perovskite solar cell 1.

[0360] The substrate 10 is usually preferably in the shape of a plate or sheet. The substrate 10 is preferably typically made of metal and / or resin. Alternatively, the substrate 10 may be a silicon semiconductor substrate. In this case, the perovskite solar cell 1 may be a tandem solar cell.

[0361] When the perovskite solar cell 1 receives light from the side of the substrate 10, the substrate 10 is formed from a transparent material. Specifically, if the strength of the solar cell 1 is important, the substrate 10 preferably contains glass. If the lightness and flexibility of the solar cell 1 are important, the substrate 10 is preferably made of resin. As the resin material for the substrate 10, polyimide, polyamide, and polyethylene terephthalate are preferred. From the viewpoint of dimensional stability, polyimide is particularly preferred. If the cost of the product is important, polyethylene terephthalate is particularly preferred. Furthermore, when the perovskite solar cell 1 receives light from the side of the second electrode layer 60, the substrate 10 may be formed from a composite material including a metal layer or the like.

[0362] The first electrode layer 20 collects holes generated in the photoelectric conversion layer 40 through the hole transport layer 30 and outputs them to the outside. The first electrode layer 20 can be formed from a transparent conductive oxide (TCO) that is conductive and light-transmitting. Examples of transparent conductive oxides that can be used to form the first electrode layer 20 include indium oxide, tin oxide, zinc oxide, titanium oxide, and composite oxides thereof. Among these, indium-based composite oxides mainly composed of indium oxide, indium zinc oxide, indium tungsten oxide, indium molybdenum oxide, etc., or fluorine-doped tin oxide are preferred. Indium oxide is particularly preferred from the viewpoint of high conductivity and transparency. To improve the moldability of the hole transport layer 30, the first electrode layer 20 is preferably subjected to a surface treatment such as ozone treatment, and may have a multilayer structure on its surface having a layer of p-type oxide semiconductor mainly composed of, for example, nickel oxide, niobium oxide, etc.

[0363] One example of a method for providing phosphorus pentoxide between the first electrode layer 20 and the hole transport layer 30 is as follows: First, a solution containing phosphorus pentoxide is applied or sprayed onto the surface of the first electrode layer 20, and then the aforementioned solution containing phosphorus pentoxide adhering to the surface of the first electrode layer 20 is dried to create a layer of phosphorus pentoxide on the surface of the first electrode layer 20, or to make it scattered.

[0364] By attaching phosphorus pentoxide to the surface of the first electrode layer 20 as described above, and then providing the hole transport layer 30 on the first electrode layer 20, phosphorus pentoxide can be present between the first electrode layer 20 and the hole transport layer 30.

[0365] The solvent contained in the phosphorus pentoxide solution is not particularly limited as long as it does not dissolve the phosphorus pentoxide and react with it. Examples of solvents that dissolve phosphorus pentoxide include solvents described later that may be included in the liquid composition used to form the hole transport layer 30, and which do not have functional groups that can dissociate protons, such as hydroxyl groups, mercapto groups, and carboxyl groups.

[0366] The hole transport layer 30 effectively transfers holes generated in the photoelectric conversion layer 40 to the first electrode layer 20. Preferably, the hole transport layer 30 is a self-assembled monolayer containing a hole transport material having bonding groups that exert an attractive interaction with the first electrode layer or are capable of forming bonds with the first electrode layer.

[0367] The hole transport material is preferably a compound in which the difference between the HOMO (Highest Occupied Molecular Orbital) of the hole transport material and the VB edge (Valence Band) of the perovskite compound constituting the photoelectric conversion layer 40 is small.

[0368] The above difference is preferably 0.00 to 1.00 eV, more preferably 0.00 to 0.50 eV, and even more preferably 0.00 to 0.30 eV.

[0369] HOMO and LUMO (Lowest Unoccupied Molecular Orbital) can be determined by photoelectron spectroscopy or quantum chemical calculations based on density functional theory.

[0370] As the exchange-correlation functional, B3LYP can be suitably used. For basis functions, 6-311G(d) can be suitably used for optimizing the molecular structure, and 6-311++G(d,p) can be suitably used for calculating the energy.

[0371] As the hole transport material, any compound that has been conventionally used to form the hole transport layer in perovskite solar cells can be used without particular limitation. Preferably, the hole transport material is a compound having an atomic group involved in hole transport and the above-mentioned bonding group.

[0372] Examples of atomic groups involved in hole transport include aromatic compounds containing a triphenylamine skeleton such as Spiro-MeOTAD (CAS number: 207739-72-8), TOP-HTM-α1 (CAS number: 872466-50-7), and TOP-HTM-α2 (CAS number: 2411528-61-3); aromatic compounds containing a carbazole skeleton such as 2PACz (CAS number: 20999-38-6), 4PACz (CAS number: 20999-36-4), MeO-2PACz (CAS number: 2922526-56-3), and Me-2PACz (CAS number: 2747959-96-0); compounds containing a phenothiazine skeleton; compounds containing a thiophene skeleton; and compounds containing a diarylamine skeleton.

[0373] A suitable bonding group is the group represented by the following formula (A): -R １ -R ２ ... (A)

[0374] R １ R is a divalent organic group with 1 to 12 carbon atoms. ２ However, these are phosphonic acid groups, carboxyl groups, sulfonic acid groups, boric acid groups, hydroxyl groups, amino groups, silyl groups, or mercapto groups.

[0375] R １ A divalent organic group may contain heteroatoms in addition to carbon and hydrogen atoms. Examples of heteroatoms include O, N, S, halogen atoms, P, B, and Si.

[0376] R １ The divalent organic group is preferably a hydrocarbon group. The number of carbon atoms in the hydrocarbon group is not particularly limited, but is preferably 1 to 12, and more preferably 1 to 6.

[0377] R １ The hydrocarbon group can be an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a combination of an aliphatic hydrocarbon group and an aromatic hydrocarbon group.

[0378] If the hydrocarbon group is an aliphatic hydrocarbon group, the structure of the aliphatic hydrocarbon group may be linear, cyclic, or a combination of linear and cyclic.

[0379] R １ Preferred specific examples of aliphatic hydrocarbon groups include methylene group, ethane-1,2-diyl group (ethylene group), ethane-1,1-diyl group, propane-1,3-diyl group (propylene group), propane-1,2-diyl group (methylethylene group), propane-2,2-diyl group, butane-1,4-diyl group, butane-1,3-diyl group, butane-1,2-diyl group, pentane-1,5-diyl group, and hexane-1,6-diyl group.

[0380] Among these groups, methylene group, ethane-1,2-diyl group (ethylene group), propane-1,3-diyl group (propylene group), butane-1,4-diyl group, and butane-1,3-diyl group (methylpropylene group) are preferred, and ethane-1,2-diyl group (ethylene group), propane-1,3-diyl group (propylene group), and butane-1,3-diyl group (methylpropylene group) are more preferred.

[0381] R １ Preferred specific examples of aromatic hydrocarbon groups include p-phenylene group, m-phenylene group, naphthalene-2,6-diyl group, naphthalene-2,7-diyl group, naphthalene-1,4-diyl group, naphthalene-1,5-diyl group, naphthalene-1,7-diyl group, biphenyl-4,4'-diyl group, biphenyl-3,4'-diyl group, and biphenyl-3,3'-diyl group.

[0382] R ２ These are phosphonic acid groups, carboxyl groups, sulfonic acid groups, boric acid groups, hydroxyl groups, amino groups, silyl groups, or mercapto groups. Silyl groups are typically reactive silicon groups that can produce silanol groups by hydrolysis. Such reactive silicon groups have hydrolyzable groups bonded to silicon atoms.

[0383] Specific examples of hydrolyzable groups include halogen atoms, alkoxy groups, acyloxy groups, ketoximate groups, amino groups, amide groups, acid amide groups, aminooxy groups, mercapto groups, and alkenyloxy groups. Among these, alkoxy groups, acyloxy groups, ketoximate groups, and alkenyloxy groups are preferred, and alkoxy groups such as methoxy groups and ethoxy groups are more preferred because they are mildly hydrolyzable and easy to handle.

[0384] Specific examples of reactive silicon groups include dimethoxymethylsilyl group, diethoxymethylsilyl group, trimethoxysilyl group, triethoxysilyl group, dimethoxyphenylsilyl group, methoxymethyldimethoxysilyl group, methoxymethyldiethoxysilyl group, triisopropenyloxysilyl group, and triacetoxysilyl group. Among these, dimethoxymethylsilyl group, trimethoxysilyl group, and methoxymethyldimethoxysilyl group are preferred.

[0385] Since hole transport materials are easy to obtain and prepare, and the hole transport layer 30 is easily formed, in formula (A), R １ However, it is an alkylene group with 1 to 6 carbon atoms, R ２ It is preferable that the group is a phosphonic acid group.

[0386] Suitable specific examples of hole transport materials include N-(2-phosphonoethyl)carbazole (2PACz), N-(2-phosphonoethyl)-3,6-dimethoxycarbazole (MeO-2PACz), N-(2-phosphonoethyl)-3,6-dimethylcarbazole (Me-2PACz), N-(3-phosphonopropyl)carbazole (3PACz), N-(3-phosphonopropyl)-3,6-dimethoxycarbazole (MeO-3PACz), N-(3-phosphonopropyl)-3,6-dimethylcarbazole (Me-3PACz), N-(4-phosphonobutyl)carbazole (4PACz), N-(4-phosphonobutyl)-3,6-dimethoxycarbazole (MeO-4PACz), and N-(4-phosphonobutyl)-3,6-dimethylcarbazole (Me-4PACz).

[0387] Among these, 2PACz, MeO-2PACz, Me-2PACz, MeO-4PACz, and Me-4PACz are more preferred.

[0388] The hole transport layer 30 may contain, in addition to the hole transport material, phosphonic acid compounds such as n-butylphosphonic acid, n-pentylphosphonic acid, n-hexylphosphonic acid, n-octylphosphonic acid, n-decylphosphonic acid, n-octadecylphosphonic acid, 2-ethylhexylphosphonic acid, methoxymethylphosphonic acid, 3-acryloyloxypropylphosphonic acid, 11-hydroxyundecylphosphonic acid, and 1H,1H,2H,2H-perfluorophosphonic acid, as well as other compounds such as acetic acid, propionic acid, isobutyric acid, nonanoic acid, fluoroacetic acid, α-chloropropionic acid, and glyoxylic acid. These compounds do not constitute the hole transport material. They may be used individually or in combination of two or more.

[0389] The hole transport layer 30 is formed, for example, by coating a liquid composition containing a hole transport material onto the first electrode layer and drying the coated film.

[0390] When the hole transport layer 30 contains the aforementioned phosphorus pentoxide, a liquid composition containing the hole transport material and phosphorus pentoxide is applied to the first electrode layer, and the applied film is dried to form the hole transport layer 30.

[0391] If the hole transport layer 30 contains phosphorus pentoxide, the amount of phosphorus pentoxide in the hole transport layer 30 is not particularly limited as long as the desired effect is not impaired.

[0392] In terms of achieving both high photoelectric conversion efficiency and durability in the perovskite solar cell 1, the amount of phosphorus pentoxide contained in the hole transport layer 30 is preferably 0.00001% to 95% by mass, more preferably 0.00001% to 50% by mass, and even more preferably 0.0001% to 30% by mass, relative to the mass of the hole transport layer 30.

[0393] The liquid composition used to form the hole transport layer 30 typically contains an organic solvent. Examples of organic solvents include alcohols such as methanol, ethanol, 2-methoxyethanol, isopropanol, and butanol; ethers such as diethyl ether, diisopropyl ether, tetrahydrofuran, 4-methyltetrahydropyran, 2-methyltetrahydrofuran, and cyclopentyl methyl ether; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; amides such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); esters such as ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isoamyl acetate, and γ-butyrolactone (GBL); nitriles such as acetonitrile, propionitrile, and 3-methoxypropionitrile; aromatic compounds such as benzene, toluene, chlorobenzene, and nitrobenzene; chlorinated hydrocarbons such as dichloromethane, chloroform, and 1,2-dichloroethane; and fluorinated hydrocarbons such as chlorofluorocarbons, hydrochlorofluorocarbons, and hydrofluorocarbons. These can be used individually or in combination of two or more.

[0394] The total concentration of the materials constituting the self-assembled monolayer contained in the liquid composition is preferably 5.0 mg / mL or less.

[0395] Furthermore, if the liquid composition contains phosphorus pentoxide, the phosphorus pentoxide content is preferably 95% by mass or less, and more preferably 0.00001% by mass or more and 50% by mass or less, relative to the mass of the material constituting the self-assembled monolayer.

[0396] Furthermore, the above liquid composition may also contain a perovskite precursor, described later, which is used to form the photoelectric conversion layer 40. When using a liquid composition containing a perovskite precursor, the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously by coating the liquid composition onto the first electrode layer 20, drying it, and crystallizing the perovskite precursor. In this case, during the process of forming the photoelectric conversion layer 40, compounds such as hole transport materials contained in the liquid composition form a self-assembled monolayer on the first electrode layer 20.

[0397] A liquid composition containing materials constituting a self-assembled monolayer and a perovskite precursor can also be made to contain phosphorus pentoxide.

[0398] When forming a hole transport layer 30 and a photoelectric conversion layer 40 using a liquid composition containing a material constituting a self-assembled monolayer, a perovskite precursor, and phosphorus pentoxide, both the hole transport layer 30 and the photoelectric conversion layer 40 contain phosphorus pentoxide.

[0399] Furthermore, phosphorus pentoxide may be present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0400] One example of a method for providing phosphorus pentoxide between the hole transport layer 30 and the photoelectric conversion layer 40 is as follows: First, a solution containing phosphorus pentoxide is applied or sprayed onto the surface of the hole transport layer 30, and then the aforementioned solution containing phosphorus pentoxide adhering to the surface of the hole transport layer 30 is dried to create a layer of phosphorus pentoxide on the surface of the hole transport layer 30, or to make it scattered. Alternatively, phosphorus pentoxide may be attached to the surface of the hole transport layer 30 by various vapor deposition techniques.

[0401] By attaching phosphorus pentoxide to the surface of the hole transport layer 30 as described above, and then providing the photoelectric conversion layer 40 on top of the hole transport layer 30, phosphorus pentoxide can be present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0402] The solvent contained in the phosphorus pentoxide solution is not particularly limited as long as it does not dissolve the phosphorus pentoxide and react with it. Examples of solvents that dissolve phosphorus pentoxide include the aforementioned solvents that may be included in the liquid composition used to form the hole transport layer 30, and which do not have functional groups that can dissociate protons, such as hydroxyl groups, mercapto groups, and carboxyl groups.

[0403] Furthermore, it is preferable that a passivation material be present between the hole transport layer 30 and the photoelectric conversion layer 40. The passivation material between the hole transport layer 30 and the photoelectric conversion layer 40 is not shown in Figure 1.

[0404] Phosphorus pentoxide and a passivation material may be present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0405] The passivation material is an organic compound that suppresses defects in the photoelectric conversion layer 40 by interacting with anionic and cationic species on the surface and / or inside the photoelectric conversion layer 40. By passivating the defects in the photoelectric conversion layer 40, the recombination of charge and holes is suppressed, and the photoelectric conversion efficiency is improved.

[0406] The passivation material may exist as a layer of a certain thickness on the surface of the photoelectric conversion layer 40, or it may exist as a single molecule or a composite of multiple molecules inside the photoelectric conversion layer 40 (for example, inside the perovskite crystal bulk or at the grain boundaries).

[0407] The mode of presence of the passivation material in the photoelectric conversion layer 40 may be any of the above modes. In any of the above modes, the photoelectric conversion efficiency of the perovskite solar cell 1 is improved.

[0408] When the passivation material is present as a layer on the surface of the photoelectric conversion layer 40, the surface of the photoelectric conversion layer 40 is passivated by applying the passivation material to the interface between the hole transport layer 30 and the photoelectric conversion layer 40, and / or the interface between the electron transport layer 50 and the photoelectric conversion layer 40.

[0409] In this case, the layer made of passivation material may be present in at least a part of the main surface of the photoelectric conversion layer 40, or it may be present throughout the entire surface, and it is preferable that it is present throughout the entire main surface of the photoelectric conversion layer 40.

[0410] When the passivation material exists inside the photoelectric conversion layer 40 as a single molecule or a composite of multiple molecules, the interaction between the passivation material (as a single molecule or composite of multiple molecules) and the perovskite crystal causes the defects inside the photoelectric conversion layer 40 to be passivated. In this case, typically, the passivation material acts on the crystal lattice of the perovskite compound inside the photoelectric conversion layer 40, causing the grain boundaries and the like to be passivated.

[0411] The passivation material is not particularly limited as long as the desired effect is not impaired. The passivation material can be appropriately selected from various compounds that have been conventionally used as passivation materials in perovskite solar cells. Suitable examples of passivation materials include various amines or their hydrohalides. Examples of hydrohalides include hydrofluoric acid, hydrochloride, hydrobromide, and hydroiodide, with hydrobromide and hydroiodide being preferred, and hydroiodide being more preferred.

[0412] Suitable examples of passivation materials include n-butylamine hydrobromide, n-butylamine hydroiodide, n-hexylamine hydrobromide, n-hexylamine hydroiodide, n-decylamine hydrobromide, n-octadecylamine hydroiodide, pyridine hydrobromide, aniline hydroiodide, hydrazine dibromide, ethylenediamine hydroiodide, phenethylamine hydroiodide, 4-fluorinated phenethylamine hydroiodide, phenylenediamine dihydrochloride, diphenylamine hydrobromide, diphenylamine hydroiodide, benzylamine hydroiodide, and 4-diphenylaminophenethylamine hydroiodide.

[0413] Fluorine-containing amine compounds and their salts are also preferred as passivation materials. Preferred specific examples of fluorine-containing amine compounds include, for example, compounds having a fluorinated aromatic group and an amino acid group, such as pentafluorophenylethylalanine hydroiodide, and their salts; fluoroalkylamines such as 6,6,6,5,5,4,4,3,3,2,2-undekafluorohexylamine hydroiodide and 5,5,5,4,4,3,3,2,2-nonafluoropentylamine hydroiodide, and their salts; and compounds having a fluorinated aromatic group and an amino group, such as 4-fluorophenylethylamine hydroiodide, and their salts.

[0414] When a passivation material is present between the hole transport layer 30 and the photoelectric conversion layer 40, a thin film of the passivation material is formed by coating the hole transport layer 30 with a passivation material solution containing the passivation material and an organic solvent, and then drying it. The same solvent used for forming the hole transport layer 30 described above is preferably used as the organic solvent.

[0415] The coating method is not particularly limited. Coating can be performed using, for example, a spin coater, die coater, or bar coater.

[0416] The temperature during application is not particularly limited, but -20°C to 200°C is preferred, and 0°C to 150°C is more preferred.

[0417] The application time is not particularly limited, but 1 second to 24 hours is preferred, and 5 seconds to 1 hour is more preferred.

[0418] Furthermore, by including a passivation material in the liquid composition containing the materials constituting the self-assembled monolayer described above, a layer made of the passivation material can be formed on the surface of the hole transport layer 30.

[0419] The photoelectric conversion layer 40 contains a perovskite compound that performs photoelectric conversion and absorbs incident light to generate photocarriers. The perovskite compound contained in the photoelectric conversion layer 40 is not particularly limited as long as the desired effect is not impaired, and can be appropriately selected from well-known compounds. As a preferred example, the perovskite compound contains an organic atomic group A containing at least one of a monovalent organic ammonium ion and an amidinium-based ion, a metal atom B that generates a divalent metal ion, and a halogen atom X containing at least one of iodide ion I, bromide ion Br, chloride ion Cl, and fluoride ion F, and ABX ３ Compounds represented by can be used. Organic group A is not particularly limited as long as the desired effect is not impaired, and can be appropriately selected from well-known organic compounds. Examples of organic group A include methylammonium MA (CH ３ NH ３ ), formamidinium FA (CH(NH ２ ) ２ (CH ５ N ２ Examples include:

[0420] The metal atom B is not particularly limited as long as it is a metal atom that has been conventionally used in the formation of perovskite compounds. Preferred metal atoms B include lead (Pb) and tin (Sn). When the power generation efficiency of the perovskite solar cell 1 is important, it is preferable that the metal atom B is mainly lead. The lower limit of the lead content in metal atom B is preferably 50% by mass, more preferably 80% by mass, and even more preferably 90% by mass, in order to achieve the desired performance. On the other hand, when the environmental impact of lead is important, it is preferable that the metal atom B is mainly tin (Sn). The lower limit of the tin content in metal atom B is preferably 50% by mass, more preferably 80% by mass, and especially preferably 90% by mass, in order to achieve the desired performance.

[0421] The halogen atom is not particularly limited. At least one of iodide I, bromide Br, and chloride Cl is preferred as the halogen atom X. Furthermore, substituting part or all of the organic atomic group A with alkali metal Am has also been considered, and such perovskite compounds can also be used. The alkali metal Am is not particularly limited. Preferred alkali metal Ams include potassium K, cesium Cs, and rubidium Rb. Among these, cesium Cs and rubidium Rb are preferred as alkali metal Ams when durability and water resistance of the perovskite solar cell 1 are important, and cesium Cs is particularly preferred from the viewpoint of cost and availability.

[0422] Specifically, preferred perovskite compounds include, for example, MAPbI ３ MAPbBr ３ MAPbCl ３ Methylammonium lead halide (MAPbX) ３ ), and FAPbi ３ FAPbBr ３ , and FAPbCl ３ Lead formamidine halogens (FAPbX) ３ ) are examples. Note that halogen atoms X may contain multiple types, and FA may contain both methylammonium and formamidinium as organic atom group A. ｙ MA １－ｙ PbX ３ It may also be included. In addition, if it contains the alkali metal Am, Am ｙ FA ｚ MA １－ｙ－ｚ PbX ３ Am ｙ FA １－ｙ PbX ３ Examples include the following. Am may be a single type of Cs, Rb, or K, or it may contain multiple types (where y and z are real numbers such that 0 ≤ y and z ≤ 1).

[0423] When a passivation material is present between the photoelectric conversion layer 40 and the electron transport layer 50, recombination of photocarriers at the interface between the photoelectric conversion layer 40 and the electron transport layer 50 is prevented, and the arrival of electrons to the electron transport layer 50 is promoted.

[0424] The passivation material placed between the photoelectric conversion layer 40 and the electron transport layer 50 can be the same material as the passivation material placed between the hole transport layer 30 and the photoelectric conversion layer 40.

[0425] As the passivation material to be placed between the photoelectric conversion layer 40 and the electron transport layer 50, the above-mentioned amine hydrohalides, amines having alkyl fluoride, or hydrohalides thereof are preferred.

[0426] As mentioned above, the passivation material can be an amine compound rather than a hydrohalide, but it will still produce the desired effect. In this case, the amine compound interacts with lead ions and other elements that form the perovskite crystal through the lone pair of electrons on the nitrogen atom, thereby preventing charge recombination.

[0427] When a passivation material is present between the photoelectric conversion layer 40 and the electron transport layer 50, it can be formed by coating the photoelectric conversion layer 40 with a passivation material solution containing the passivation material and an organic solvent, and then drying it, similar to the passivation material present between the hole transport layer 30 and the photoelectric conversion layer 40.

[0428] When the perovskite precursor solution used to form the photoelectric conversion layer 40 contains the aforementioned phosphorus pentoxide, the photoelectric conversion layer 40 can be formed by coating the perovskite precursor solution onto the hole transport layer 30, drying it, and crystallizing the perovskite precursor, thereby containing phosphorus pentoxide in one or more of its surfaces, polycrystalline interfaces, and interior.

[0429] When a passivation material is included in the perovskite precursor solution used to form the photoelectric conversion layer 40, the passivation material can be present on the surface and / or inside the photoelectric conversion layer 40 by coating the perovskite precursor solution onto the hole transport layer 30, drying it, and crystallizing the perovskite precursor.

[0430] When the perovskite precursor solution used to form the photoelectric conversion layer 40 contains a passivation material and phosphorus pentoxide, the passivation material and phosphorus pentoxide can be present on the surface and / or inside the photoelectric conversion layer 40 by coating the perovskite precursor solution onto the hole transport layer 30, drying it, and crystallizing the perovskite precursor.

[0431] Furthermore, the aforementioned liquid composition containing the material constituting the self-assembled monolayer may also contain a perovskite precursor for forming the photoelectric conversion layer 40 and a passivation material. In this case, by coating and drying the liquid composition on the first electrode layer 20 and crystallizing the perovskite precursor, the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously, while the passivation material can be present on the surface and / or inside the photoelectric conversion layer 40.

[0432] Furthermore, the aforementioned liquid composition containing the material constituting the self-assembled monolayer may also contain a perovskite precursor for forming the photoelectric conversion layer 40, a passivation material, and phosphorus pentoxide. In this case, by coating and drying the liquid composition on the first electrode layer 20 and crystallizing the perovskite precursor, the hole transport layer 30 and the photoelectric conversion layer 40 can be formed simultaneously, while phosphorus pentoxide can be present on the surface and / or inside the hole transport layer, and the passivation material and phosphorus pentoxide can be present on the surface and / or inside the photoelectric conversion layer 40.

[0433] In terms of achieving both high photoelectric conversion efficiency and durability in the perovskite solar cell 1, the amount of phosphorus pentoxide contained in the photoelectric conversion layer 40 is preferably 0.00001% to 95% by mass, more preferably 0.0001% to 50% by mass, and even more preferably 0.0001% to 30% by mass, relative to the mass of the photoelectric conversion layer 40. Furthermore, in the photoelectric conversion layer 40, the ratio of the mass of phosphorus pentoxide to the mass of the perovskite compound may be arbitrarily adjusted from the viewpoint of balancing power generation performance and durability, but for example, it is preferably 0.0001% to 100% by mass, and more preferably 0.001% to 50% by mass.

[0434] When the perovskite precursor solution contains a passivation material and a perovskite precursor, fluorine-containing amine compounds and their salts are preferred as passivation materials because they are easily precipitated at the interface and surface of the perovskite polycrystal by utilizing the hydrophobic interaction of fluorine atoms. The fluorine content in the fluorine-containing amine compound is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, as the mass of fluorine atoms relative to the molecular weight of each compound. When the fluorine-containing amine compound and its salt contain fluorine atoms in the above ratios, the fluorine-containing amine compound is easily precipitated on the perovskite crystal surface by sufficient hydrophobic interaction.

[0435] Phosphorus pentoxide may be present between the photoelectric conversion layer 40 and the electron transport layer 50.

[0436] One example of a method for providing phosphorus pentoxide between the photoelectric conversion layer 40 and the electron transport layer 50 is as follows: First, a solution containing phosphorus pentoxide is applied or sprayed onto the surface of the photoelectric conversion layer 40, and then the aforementioned solution containing phosphorus pentoxide adhering to the surface of the photoelectric conversion layer 40 is dried to create a layer of phosphorus pentoxide on the surface of the photoelectric conversion layer 40, or to make it scattered. Alternatively, phosphorus pentoxide may be attached to the surface of the photoelectric conversion layer 40 by various vapor deposition techniques.

[0437] By attaching phosphorus pentoxide to the surface of the photoelectric conversion layer 40 as described above, and then providing the electron transport layer 50 on the photoelectric conversion layer 40, phosphorus pentoxide can be present between the photoelectric conversion layer 40 and the electron transport layer 50.

[0438] The solvent contained in the phosphorus pentoxide solution is not particularly limited as long as it does not dissolve the phosphorus pentoxide and react with it. Examples of solvents that dissolve phosphorus pentoxide include the aforementioned solvents that may be included in the liquid composition used to form the hole transport layer 30, and which do not have functional groups that can dissociate protons, such as hydroxyl groups, mercapto groups, and carboxyl groups.

[0439] The electron transport layer 50 effectively transmits electrons to the second electrode layer 60. The material constituting the electron transport layer 50 is not particularly limited as long as the desired effect is not impaired. The material constituting the electron transport layer 50 can be appropriately selected from various compounds that have been conventionally used to form electron transport layers in perovskite solar cells. The electron transport layer 50 is preferably formed from an electron transport material mainly composed of, for example, fullerene or naphthalene diimide. Examples of fullerenes include C60, C70, their hydrides, oxides, metal complexes, alkyl groups, etc., derivatives to which such as PCBM ([6,6]-Phenyl-C61-Butyric Acid Methyl Ester) can be added. In addition, a hole block layer of bathocuproine (BCP), lithium fluoride (LiF), or magnesium fluoride (MgF) can be placed between the electron transport layer 50 and the second electrode layer 60. ２ ), tin oxide (SnO ２ ), aluminum-doped zinc oxide (ZnO), titanium oxide (TiO ２ ) may contain. The inorganic oxide layer may be doped with another metallic material. The material of the hole block layer is not limited to these.

[0440] When the electron transport layer 50 is formed by coating a liquid composition containing an electron transport material onto the photoelectric conversion layer 40 and then drying the formed coating film, phosphorus pentoxide can be present on or inside the electron transport layer 50 by including phosphorus pentoxide together with the electron transport material in the liquid composition.

[0441] In terms of achieving both high photoelectric conversion efficiency and durability in the perovskite solar cell 1, the amount of phosphorus pentoxide contained in the electron transport layer 50 is preferably 0.00001% to 95% by mass, more preferably 0.00001% to 50% by mass, and even more preferably 0.0001% to 30% by mass, relative to the mass of the electron transport layer 50.

[0442] A phosphorus pentoxide may be present between the electron transport layer 50 and the second electrode layer 60.

[0443] One example of a method for providing phosphorus pentoxide between the electron transport layer 50 and the second electrode layer 60 is as follows: First, a solution containing phosphorus pentoxide is applied or sprayed onto the surface of the electron transport layer 50, and then the aforementioned solution containing phosphorus pentoxide adhering to the surface of the electron transport layer 50 is dried to create a layer of phosphorus pentoxide on the surface of the electron transport layer 50, or to make it scattered. Alternatively, phosphorus pentoxide may be attached to the surface of the electron transport layer 50 by various vapor deposition techniques.

[0444] By attaching phosphorus pentoxide to the surface of the electron transport layer 50 as described above, and then providing the second electrode layer 60 on the electron transport layer 50, phosphorus pentoxide can be present between the electron transport layer 50 and the second electrode layer 60.

[0445] The solvent contained in the phosphorus pentoxide solution is not particularly limited as long as it dissolves phosphorus pentoxide. Examples of solvents that dissolve phosphorus pentoxide include the aforementioned solvents, which may also include the liquid composition used to form the hole transport layer 30.

[0446] The second electrode layer 60 preferably includes a metal layer, such as copper, to reduce electrical resistance when the perovskite solar cell 1 receives light from the substrate 10 side. However, the metal constituting the metal layer is not limited to copper. Furthermore, when the perovskite solar cell 1 receives light from the second electrode layer 60 side, the second electrode layer 60 may be formed from a transparent conductive oxide.

[0447] A liquid composition comprising (A) lead halide and / or tin halide, (B) formamidine hydrohalide and / or methylamine hydrohalide, (C) organic solvent, and (D) phosphorus pentoxide can be suitably used as a liquid composition for forming the photoelectric conversion layer in a perovskite solar cell.

[0448] (A) Lead halides and / or tin halides, and (B) Formamidine hydrohalides and / or methylamine hydrohalides are so-called perovskite precursors.

[0449] (C) As organic solvents, for example, alcohols such as methanol, ethanol, and 2-methoxyethanol; amide solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); sulfoxides such as dimethyl sulfoxide (DMSO), diethyl sulfoxide, and dibutyl sulfoxide; esters such as ethyl acetate, butyl acetate, propyl acetate, isopropyl acetate, amyl acetate, and γ-butyrolactone (GBL); and aprotic polar solvents such as acetonitrile and propionitrile may be used individually or as a mixture of several types. (C) Organic solvents may also contain other types of organic solvents in addition to the organic solvents mentioned above. The boiling points of these organic solvents are preferably as low as possible because they need to be removed by distillation during the formation of perovskite crystals. Specifically, the boiling points at atmospheric pressure are preferably 300°C or lower, more preferably 200°C or lower, and even more preferably 180°C or lower.

[0450] When using an organic solvent (C) with such a boiling point, the organic solvent (C) is less likely to remain in the perovskite crystal, making it easier to manufacture a perovskite solar cell 1 with the desired performance.

[0451] (D) One or more compounds selected from the group consisting of ascorbic acid compounds, phenolic compounds, and unsaturated compounds are as described above.

[0452] The content of (A) lead halide and / or tin halide in the above liquid composition is preferably 1.0% by mass or more and 99.0% by mass or less, and more preferably 5.0% by mass or more and 90.0% by mass or less, based on the total mass of the liquid composition, in terms of solubility, growth rate of perovskite polycrystals, photoelectric conversion efficiency, and cost.

[0453] The content of (B) formamidine hydrohalide and / or methylamine hydrohalide in the above liquid composition is preferably 0.5 molar equivalents or more and 10 molar equivalents or less, and more preferably 0.8 molar equivalents or more and 5.0 molar equivalents or less, relative to the content (number of moles) of (A) lead halide and / or tin halide.

[0454] The content of (D) phosphorus pentoxide in the above liquid composition is preferably 0.001% to 50% by mass, more preferably 0.005% to 30% by mass, and more preferably 0.01% to 10% by mass, relative to the mass of the liquid composition, from the viewpoint of film formation when applying the above liquid composition to form a photoelectric conversion layer and from the viewpoint of durability of the perovskite solar cell.

[0455] The above liquid composition may contain one or more selected from the group consisting of (E) cesium halide, (F) passivation material, and (G) hole transport material. (F) passivation material and (G) hole transport material are as described above.

[0456] When the liquid composition contains (E) cesium halide, a perovskite solar cell 1 with excellent durability and water resistance can be easily obtained by forming a photoelectric conversion layer 40 using the liquid composition.

[0457] The advantages of the liquid composition including (F) a passivation material and / or (G) a hole transport material are as described above.

[0458] The content of (E) cesium halide in the above liquid composition is preferably 0 to 10 molar equivalents, and more preferably 0.01 to 5.0 molar equivalents, relative to the content (number of moles) of (A) lead halide and / or tin halide, in terms of the durability of the perovskite solar cell.

[0459] The content of (F) passivation material in the above liquid composition is preferably 0.001% by mass or more and 10% by mass or less, and more preferably 0.01% by mass or more and 5.0% by mass or less, relative to the total mass of (A) lead halide and / or tin halide and (B) formamidine hydrohalide and / or methylamine hydrohalide, in terms of photoelectric conversion efficiency, durability and cost.

[0460] The content of (G) hole transport material in the above liquid composition is preferably 0.001% by mass or more and 10% by mass or less, and more preferably 0.01% by mass or more and 5.0% by mass or less, relative to the total mass of the liquid composition, in terms of photoelectric conversion efficiency, durability, and cost.

[0461] By using the above liquid composition to form the photoelectric conversion layer 40 in the perovskite solar cell 1, a perovskite solar cell with excellent durability can be obtained.

[0462] <<Method for Manufacturing Perovskite Solar Cells>> A perovskite solar cell comprising a first electrode layer 20, a hole transport layer 30, a photoelectric conversion layer 40, an electron transport layer 50, and a second electrode layer 60 in this order can be manufactured by a method that includes forming the photoelectric conversion layer 40 by removing volatile components from a coating film containing a liquid composition containing the above-mentioned components (A) to (D).

[0463] A preferred method for manufacturing a perovskite solar cell 1 is a method comprising: coating a first electrode layer 20 formed on one main surface of a plate-shaped or sheet-shaped substrate 10 with the aforementioned liquid composition to form a hole transport layer 30; forming a photoelectric conversion layer 40 containing a perovskite compound on the hole transport layer 30 by removing volatile components from a coating film containing the liquid composition containing the above components (A) to (D); forming an electron transport layer 50 on the photoelectric conversion layer 40; and forming a second electrode layer 60 on the electron transport layer 50.

[0464] Specifically, the perovskite solar cell 1 can be manufactured by the embodiment of the solar cell manufacturing method shown in Figure 2. The solar cell manufacturing method of this embodiment comprises a first electrode layer formation step (step S11), a hole transport layer formation step (step S12), a precursor liquid coating step (step S13), a crystallization step (step S14), an electron transport layer formation step (step S15), and a second electrode layer formation step (step S16).

[0465] The embodiment of the solar cell manufacturing method shown in Figure 2 may include a first phosphorus pentoxide application step (step S11a, not shown) between the first electrode layer formation step (step S11) and the hole transport layer formation step (step S12), in which a solution containing phosphorus pentoxide is applied or sprayed onto the surface of the first electrode layer 20, and then the aforementioned solution containing phosphorus pentoxide adhering to the surface of the first electrode layer 20 is dried to cause phosphorus pentoxide to be present in a layer or scattered on the surface of the first electrode layer 20.

[0466] The embodiment of the solar cell manufacturing method shown in Figure 2 may include a second phosphorus pentoxide application step (step S12a, not shown) between the hole transport layer formation step (step S12) and the precursor liquid coating step (step S13), in which a solution containing phosphorus pentoxide is applied or sprayed onto the surface of the hole transport layer 30, and the aforementioned phosphorus pentoxide-containing solution adhering to the surface of the hole transport layer 30 is dried to cause phosphorus pentoxide to be present in a layer or scattered on the surface of the hole transport layer 30.

[0467] The embodiment of the solar cell manufacturing method shown in Figure 2 may include a third phosphorus pentoxide application step (step S14a, not shown) between the crystallization step (step S14) and the electron transport layer formation step (step S15), in which a solution containing phosphorus pentoxide is applied or sprayed onto the surface of the photoelectric conversion layer 40, and then the aforementioned solution containing phosphorus pentoxide adhering to the surface of the photoelectric conversion layer 40 is dried to cause phosphorus pentoxide to be present in a layer or scattered on the surface of the photoelectric conversion layer 40.

[0468] The embodiment of the solar cell manufacturing method shown in Figure 2 may include a fourth phosphorus pentoxide application step (step S14a, not shown) between the electron transport layer formation step (step S15) and the second electrode layer formation step (step S16), in which a solution containing phosphorus pentoxide is applied or sprayed onto the surface of the electron transport layer 50, and then the aforementioned solution containing phosphorus pentoxide adhering to the surface of the electron transport layer 50 is dried to cause phosphorus pentoxide to be present in a layer or scattered on the surface of the electron transport layer 50.

[0469] The embodiment of the solar cell manufacturing method shown in Figure 2 may include a first passivation material coating step (step S01, not shown in Figure 2) between the hole transport layer formation step (step S12) and the precursor liquid coating step (step S13).

[0470] Furthermore, if a precursor liquid that does not contain passivation material is used in the precursor liquid coating step (step S13), the embodiment of the solar cell manufacturing method shown in Figure 2 may include a second passivation material coating step (step S02, not shown in Figure 2).

[0471] In the hole transport layer formation step (step S12), the electron transport layer formation step (step S15), and the second electrode layer formation step (step S16), a hole transport layer 30 and an electron transport layer 50 containing phosphorus pentoxide can be formed by the method described above.

[0472] In the first electrode layer formation step S11, a first electrode layer 20 is formed on the main surface of one side of the substrate 10. The first electrode layer 20 can be laminated using a vacuum deposition technique such as sputtering. In addition, in the first electrode layer formation step, it is preferable to modify the surface of the deposited first electrode layer 20 in order to promote the formation of the hole transport layer 30 in the next step. Specific methods for modifying the surface of the first electrode layer 20 include, for example, surface hydroxylation by ultraviolet-ozone treatment or ozonated water washing, deposition of oxides such as nickel oxide that facilitate the growth of self-assembled films using a vacuum deposition technique such as sputtering, deposition of oxide nanoparticles using a coating technique, and heat treatment to activate the surface and remove impurities so that self-assembled films can grow easily.

[0473] In step S12, the hole transport layer formation step, the hole transport layer 30 is laminated onto the first electrode layer 20. The hole transport layer 30 can be formed by coating a solution containing the material constituting the hole transport layer 30 and an organic solvent, and then drying. The drying temperature is preferably 50°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher. The drying time is preferably 1 minute or more, more preferably 5 minutes or more, and even more preferably 10 minutes or more. When drying is performed under the above conditions, the organic solvent is sufficiently removed from the coated film, making it easier to obtain the desired crystals in the subsequent step of forming the perovskite polycrystal.

[0474] After forming the hole transport layer 30 in step S12, a first passivation material coating step (step S01) may be performed as needed to coat the hole transport layer 30 with passivation material. In the first passivation material coating step (step S01), a passivation material solution containing passivation material and an organic solvent is coated onto the hole transport layer 30, and then the coated film is dried. In this case, the passivation material can be present on the hole transport layer 30.

[0475] The passivation material solution can be applied using, for example, a spin coater, die coater, and bar coater.

[0476] Furthermore, in step S12, the passivation material can also be present on the hole transport layer 30 by coating it with a liquid composition containing the material constituting the hole transport layer 30 and the passivation material to form the hole transport layer 30.

[0477] In the precursor liquid coating step S13, a liquid composition containing the above components (A) to (D) is coated onto the laminate of the substrate 10, the first electrode layer 20, and the hole transport layer 30 as a perovskite precursor liquid.

[0478] When step S01 is performed, the liquid composition containing components (A) to (D) described above is coated onto the passivation material applied on the hole transport layer 30.

[0479] The liquid composition containing components (A) to (D) can be applied using, for example, a spin coater, die coater, and bar coater.

[0480] A liquid composition containing components (A) to (D) comprises (C) a solvent, (A) lead halide and / or tin halide as perovskite precursors that form a perovskite compound that performs photoelectric conversion, and (B) formamidine hydrohalide and / or methylamine hydrohalide, and (D) phosphorus pentoxide. A liquid composition containing components (A) to (D) may also contain perovskite precursors other than components (A) and (B) along with components (A) and (B). Furthermore, a liquid composition containing components (A) to (D) may further contain a hydrogen chloride salt that promotes the growth of crystals of the perovskite compound.

[0481] By using a liquid composition containing components (A) to (D), a photoelectric conversion layer 40 containing (D) phosphorus pentoxide can be formed in steps S13 and S14.

[0482] The photoelectric conversion layer 40 may be formed using a liquid composition containing (G) a hole transport material and a perovskite precursor as materials constituting the hole transport layer 30. In this case, step S12 for forming the hole transport layer 30 can be omitted. This is because the hole transport layer 30 is formed in the process of forming the photoelectric conversion layer 40 in steps S13 and S14. By using a liquid composition containing (G) a hole transport material and a perovskite precursor, the photoelectric conversion layer 40 containing (D) phosphorus pentoxide and the hole transport layer 30 containing component (D) can be formed simultaneously in steps S13 and S14.

[0483] A passivation material may be further added to a liquid composition containing (G) a hole transport material, a perovskite precursor, and component (D) as materials constituting the hole transport layer 30. When using a liquid composition containing the materials constituting the hole transport layer 30, a perovskite precursor, and a passivation material, the photoelectric conversion layer 40 can be formed while forming the hole transport layer 30 by steps S13 and S14, and the passivation material and component (D) can be present on the surface and / or inside the photoelectric conversion layer 40.

[0484] The concentration of the liquid composition containing components (A) to (D) is related to the conditions of the crystallization process. The solid content concentration of the liquid composition containing components (A) to (D) is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more.

[0485] When the solid content concentration of the liquid composition containing components (A) to (D) is such that the organic solvent can be volatilized with less energy when forming the photoelectric conversion layer 40, the perovskite solar cell 1 can be manufactured at low cost while reducing the environmental impact.

[0486] Generally, a metal halide BX and a halogenated organic compound AX are used as the perovskite precursor in predetermined proportions, preferably a metal halide BX, a halogenated organic compound AX, and, if necessary, an alkali metal halide AmX are used in predetermined proportions. As the metal halide BX, lead halide and / or tin halide are preferably used. As the halogenated organic compound AX, formamidine hydrohalides and methylamine hydrohalides are preferably used. As the alkali metal halide AmX, cesium halides such as cesium iodide are preferably used. The molar concentration of metal atom B is preferably in excess of 0.5 mol% to 10 mol% relative to the sum of the molar concentration of the organic compound and the molar concentration of alkali metal Am. This makes it possible to expel other materials to the front and back interfaces of the perovskite precursor solution during the crystallization process, and to suppress the decrease in photoelectric conversion efficiency caused by the retention of other materials in the perovskite crystal. The amounts used in a liquid composition containing components (A) to (D), namely (A) lead halide and / or tin halide, and (B) formamidine hydrohalide and / or methylamine hydrohalide, are determined appropriately considering the above.

[0487] When the liquid composition containing components (A) to (D) also contains a passivation material, the recombination of photocarriers (holes and electrons) at the interface of the photoelectric conversion layer 40 is suppressed by the action of the passivation material present on and / or inside the photoelectric conversion layer 40.

[0488] Hydrochlorides promote the crystallization of perovskite compounds and increase the grain size of the perovskite crystals. This reduces the area of ​​grain boundaries in the photoelectric conversion layer 40, suppressing the decrease in photoelectric conversion efficiency due to impurities between the perovskite crystals. Examples of hydrochlorides include methylamine hydrochloride (MACl), formamidine hydrochloride (FACl), and methylenediaminium hydrochloride (MDACl). ２) etc. are used. The portion other than the hydrogen chloride is preferably smaller than or equal to the crystal lattice of the perovskite crystal and has an amino group. The concentration of the hydrogen chloride in the liquid composition containing components (A) to (D) may be 1 mol% to 40 mol% with respect to the molar concentration of the metal atom B ion of the perovskite compound.

[0489] In the crystallization step S14, the coating film containing the liquid composition with components (A) to (D) is dried (the solvent is evaporated) to generate crystals of the perovskite compound. This forms a photoelectric conversion layer 40 mainly composed of the perovskite compound.

[0490] When the liquid composition containing components (A) to (D) contains a passivation material, a photoelectric conversion layer 40 is formed, and the passivation material can be present on the surface and / or inside the photoelectric conversion layer 40. As a method to promote the formation of crystals of the perovskite compound in the coating film containing the liquid composition containing components (A) to (D), it is preferable to employ, for example, poor solvent quenching, vacuum quenching, gas quenching, laser treatment, etc. In the crystallization step of step S14, the coating film containing the liquid composition containing components (A) to (D) may be further heated after drying.

[0491] After forming the photoelectric conversion layer 40 in steps S13 and S14, a second passivation material coating step (step S02) may be performed as needed to provide the passivation material on the main surface of the photoelectric conversion layer 40 opposite to the hole transport layer 30. In the second passivation material coating step (step S02), a passivation material solution containing the passivation material and an organic solvent is coated onto the photoelectric conversion layer 40, and then the coating film is dried to provide the passivation material on the photoelectric conversion layer 40.

[0492] In step S15, the electron transport layer formation step, the electron transport layer 50 is formed by methods such as coating or vacuum deposition. A hole block layer may also be formed on the electron transport layer 50 by vacuum deposition or atomic layer deposition.

[0493] In step S16, the second electrode layer formation step, the second electrode layer 60 is formed by methods such as sputtering, vacuum deposition, plating, or coating, depending on the material being formed.

[0494] As described above, perovskite solar cells exhibit high photoelectric conversion efficiency.

[0495] Although embodiments of the present invention C have been described above, the present invention C is not limited to the embodiments described above, and various modifications and variations are possible. The solar cell according to the present invention C may include further functional layers, for example, in a perovskite solar cell, the electron transport layer may be omitted. Furthermore, the perovskite solar cell may be a tandem solar cell using a photoelectric converter such as a crystalline silicon solar cell as a substrate.

[0496] The present invention will be described in detail below based on examples, but the present invention is not limited to the following examples.

[0497] <<Examples of Invention A>> [Examples 1-17 and Comparative Examples 1-6] (Preparation of Liquid Composition) A mixture consisting of lead iodide (2.00 g), formamidine hydroiodide (0.634 g), cesium iodide (0.0834 g), methylamine hydrochloride (0.0943 g), N-(4-phosphonobutyl)-3,6-dimethoxycarbazole (MeO-4PACz) (0.00179 g), 6,6,6,5,5,4,4,3,3,2,2-undecafluorohexylamine hydroiodide (0.00086 g), N,N-dimethylformamide (2.90 g), and N-methyl-2-pyrrolidone (0.522 g) was mixed with additives of the types listed in Table 1 to obtain a liquid composition. The concentrations of the additives listed in Table 1 in the liquid composition are as shown in Table 1. In Comparative Example 1, a mixture without additives was used as the liquid composition.

[0498] (Fabrication of Perovskite Solar Cells) A glass substrate with an ITO film measuring 3 cm x 3 cm was washed in the following order: with pure water, with acetone, and with 2-propanol. The washed glass substrate was dried at 180°C for 1 hour. The dried glass substrate was cooled to room temperature. Next, the above liquid composition was applied onto the ITO film on the glass substrate using a spin coater in an environment of 24-25°C, 60-70% relative humidity, and 20.9% ± 0.2% oxygen concentration. The solvent was removed from the coated film by placing it under vacuum at room temperature for 5 minutes. Next, a photoelectric conversion layer containing a perovskite compound was formed on the ITO film on the glass substrate by heating the glass substrate on a hot plate at 120°C for 30 minutes in an environment of 60-70% relative humidity and 20.9% ± 0.2% oxygen concentration.

[0499] Furthermore, a fullerene is deposited on the photoelectric conversion layer to a thickness of 20 nm as an electron transport layer, followed by a 20 nm thick SnO layer as a buffer layer. ２ A perovskite solar cell was obtained by forming a thin film using atomic layer deposition, and then depositing copper to a thickness of 100 nm to create a second electrode layer on top of the electron transport layer.

[0500] (Durability Evaluation) The durability of perovskite solar cells formed using the liquid compositions of each example and each comparative example was evaluated using the following method. For durability evaluation, a laminate in which the electron transport layer and the second electrode layer were not formed and the photoelectric conversion layer was exposed was used.

[0501] Specifically, the durability of the perovskite solar cell was evaluated by observing the decomposition of the perovskite crystal in the photoelectric conversion layer while the above-mentioned laminate was placed in an environment of 23°C, 50% relative humidity, and 20.9% ± 0.2% oxygen concentration.

[0502] A photoelectric conversion layer with the desired power generation capacity has a metallic luster, while a photoelectric conversion layer whose power generation capacity has decreased or has no power generation capacity due to the decomposition of the perovskite crystal does not have a metallic luster. The decomposition products of the perovskite crystal exhibit a pale yellow to translucent white color. For these reasons, the durability of a perovskite solar cell can be evaluated by observing the appearance of the photoelectric conversion layer in an environment of 23°C, 50% relative humidity, and 20.9% ± 0.2% oxygen concentration.

[0503] T50 was defined as the time at which the ratio of the area with metallic luster to the area of ​​the photoelectric conversion layer fell below 50%. T50 was determined for each of the laminates formed using the liquid compositions of Examples 1 to 11 and Comparative Examples 2 to 6. T50 was also determined for the laminate formed using the liquid composition of Comparative Example 1. The durability index, as a dimensionless number, was calculated by dividing the T50 of the laminates formed using the liquid compositions of Examples 1 to 11 and Comparative Examples 1 to 6 by the T50 of the laminate formed using the liquid composition of Comparative Example 1. Based on the calculated durability index, the durability of the perovskite solar cells of each example and comparative example was evaluated according to the following criteria. The evaluation results are shown in Table 1. Evaluation 1: Index was less than 1. Evaluation 2: Index was 1. Evaluation 3: Index was greater than 1 and less than 1.5. Evaluation 4: Index was 1.5 or greater and less than 2. Evaluation 5: Index was 2 or greater.

[0504]

[0505] Table 1 shows that the durability of the perovskite solar cell of the example, which contains the aforementioned specific additive between the first electrode layer and the second electrode layer, is superior to that of the perovskite solar cell that does not contain the aforementioned specific additive between the first electrode layer and the second electrode layer. The mechanism by which the above effect is obtained by adding the specific additive in the present invention is not fully clear, but it is presumed that in the case of alcohols and phenols with higher acidity used in Examples 1 to 12 compared to aliphatic primary alcohols used in Comparative Examples 2 to 6, the stability of the perovskite crystal is increased by hydrogen bonding with the perovskite crystal layer. Furthermore, in the case of the ester compounds used in Examples 13 to 15, it is presumed that the lone pair of electrons on the oxygen atom of the carbonyl group acts as a Lewis base, stabilizing the perovskite crystal through interaction with defect sites in the perovskite crystal.

[0506] <<Examples of Invention B>> [Examples 1-18 and Comparative Examples 1-4] (Preparation of Liquid Composition) A mixture consisting of lead iodide (2.00 g), formamidine hydroiodide (0.634 g), cesium iodide (0.0834 g), methylamine hydrochloride (0.0943 g), N-(4-phosphonobutyl)-3,6-dimethoxycarbazole (MeO-4PACz) (0.00179 g), 6,6,6,5,5,4,4,3,3,2,2-undecafluorohexylamine hydroiodide (0.00086 g), N,N-dimethylformamide (2.90 g), and N-methyl-2-pyrrolidone (0.522 g) was mixed with additives of the types listed in Table 2 to obtain a liquid composition. The concentrations of the additives listed in Table 2 in the liquid composition are as shown in Table 2. In Comparative Example 1, a mixture without additives was used as the liquid composition.

[0507] (Fabrication of Perovskite Solar Cells) A glass substrate with an ITO film measuring 3 cm x 3 cm was washed in the following order: with pure water, with acetone, and with 2-propanol. The washed glass substrate was dried at 180°C for 1 hour. The dried glass substrate was cooled to room temperature. Next, the above liquid composition was applied onto the ITO film on the glass substrate using a spin coater in an environment of 24-25°C, 60-70% relative humidity, and 20.9% ± 0.2% oxygen concentration. The solvent was removed from the coated film by placing it under vacuum at room temperature for 5 minutes. Next, the glass substrate was heated on a hot plate at 120°C for 30 minutes in an environment of 60-70% relative humidity and 20.9% ± 0.2% oxygen concentration, thereby forming a photoelectric conversion layer containing a perovskite compound on the ITO film on the glass substrate.

[0508] Furthermore, a fullerene is deposited on the photoelectric conversion layer to a thickness of 20 nm as an electron transport layer, followed by a 20 nm thick SnO layer as a buffer layer. ２ A perovskite solar cell was obtained by forming a thin film using atomic layer deposition, and then depositing copper to a thickness of 100 nm to create a second electrode layer on the electron transport layer. In Comparative Examples 3 and 4, the photoelectric conversion layer could not be formed properly. Therefore, perovskite solar cells could not be manufactured in Comparative Examples 3 and 4. Furthermore, the following durability evaluations were not performed on Comparative Examples 3 and 4.

[0509] (Durability Evaluation) The durability of perovskite solar cells formed using the liquid compositions of each example and each comparative example was evaluated using the following method. For durability evaluation, a laminate in which the electron transport layer and the second electrode layer were not formed and the photoelectric conversion layer was exposed was used.

[0510] Specifically, the durability of the perovskite solar cell was evaluated by observing the decomposition of the perovskite crystal in the photoelectric conversion layer while the above-mentioned laminate was placed in an environment of 23°C, 50% relative humidity, and 20.9% ± 0.2% oxygen concentration.

[0511] A photoelectric conversion layer with the desired power generation capacity has a metallic luster, while a photoelectric conversion layer whose power generation capacity has decreased or has no power generation capacity due to the decomposition of the perovskite crystal does not have a metallic luster. The decomposition products of the perovskite crystal exhibit a pale yellow to translucent white color. For these reasons, the durability of a perovskite solar cell can be evaluated by observing the appearance of the photoelectric conversion layer in an environment of 23°C, 50% relative humidity, and 20.9% ± 0.2% oxygen concentration.

[0512] T50 was defined as the time at which the ratio of the area with metallic luster to the area of ​​the photoelectric conversion layer fell below 50%. T50 was determined for each of the laminates formed using the liquid compositions of Examples 1 to 18 and Comparative Examples 2 to 6. T50 was also determined for the laminate formed using the liquid composition of Comparative Example 1. The durability index, as a dimensionless number, was calculated by dividing the T50 of the laminate formed using the liquid composition of Comparative Example 1 by the T50 of the laminate formed using the liquid composition of Comparative Example 1. Based on the calculated durability index, the durability of the perovskite solar cells of each example and comparative example was evaluated according to the following criteria. The evaluation results are shown in Table 2. Evaluation 1: Index was less than 1. Evaluation 2: Index was 1. Evaluation 3: Index was greater than 1 and less than 1.5. Evaluation 4: Index was 1.5 or greater and less than 2. Evaluation 5: Index was 2 or greater.

[0513]

[0514] Table 2 shows that the durability of the perovskite solar cell of the example, which contains the aforementioned specific additive between the first electrode layer and the second electrode layer, is superior to that of the perovskite solar cell which does not contain the aforementioned specific additive between the first electrode layer and the second electrode layer. The mechanism by which the above effect is obtained by adding the specific additive in the present invention is not fully clear, but it is presumed that the additive used in Examples 1 to 12 has lower hygroscopicity and allows electron donation by unpaired electrons on the oxygen atom compared to succinic acid amide used in Comparative Examples 2 to 3, which is influencing the result. Furthermore, it is presumed that the phosphoric acid in Examples 13 to 18 stabilizes the perovskite crystal through hydrogen bonding with the perovskite crystal.

[0515] <<Examples of Invention C>> [Examples 1-3 and Comparative Examples 1-7] (Preparation of Liquid Composition) A mixture consisting of lead iodide (2.00 g), formamidine hydroiodide (0.634 g), cesium iodide (0.0834 g), methylamine hydrochloride (0.0943 g), N-(4-phosphonobutyl)-3,6-dimethoxycarbazole (MeO-4PACz) (0.00179 g), 6,6,6,5,5,4,4,3,3,2,2-undecafluorohexylamine hydroiodide (0.00086 g), N,N-dimethylformamide (2.90 g), and N-methyl-2-pyrrolidone (0.522 g) was mixed with additives of the types listed in Table 3 to obtain a liquid composition. The concentrations of the additives listed in Table 3 in the liquid composition are as shown in Table 3. In Comparative Example 1, a mixture without additives was used as the liquid composition.

[0516] (Fabrication of Perovskite Solar Cells) A glass substrate with an ITO film measuring 3 cm x 3 cm was washed in the following order: with pure water, with acetone, and with 2-propanol. The washed glass substrate was dried at 180°C for 1 hour. The dried glass substrate was cooled to room temperature. Next, the above liquid composition was applied onto the ITO film on the glass substrate using a spin coater in an environment of 24-25°C, 60-70% relative humidity, and 20.9% ± 0.2% oxygen concentration. The solvent was removed from the coated film by placing it under vacuum at room temperature for 5 minutes. Next, a photoelectric conversion layer containing a perovskite compound was formed on the ITO film on the glass substrate by heating the glass substrate on a hot plate at 120°C for 30 minutes in an environment of 60-70% relative humidity and 20.9% ± 0.2% oxygen concentration.

[0517] Furthermore, a fullerene is deposited on the photoelectric conversion layer to a thickness of 20 nm as an electron transport layer, followed by a 20 nm thick SnO layer as a buffer layer. ２ A perovskite solar cell was obtained by forming a thin film using atomic layer deposition, and then depositing copper to a thickness of 100 nm to create a second electrode layer on the electron transport layer. In Comparative Examples 5 to 7, the photoelectric conversion layer could not be formed properly. Therefore, perovskite solar cells could not be manufactured in Comparative Examples 5 to 7. Furthermore, the following durability evaluations were not performed for Comparative Examples 5 to 7.

[0518] (Durability Evaluation) The durability of perovskite solar cells formed using the liquid compositions of each example and each comparative example was evaluated using the following method. For durability evaluation, a laminate in which the electron transport layer and the second electrode layer were not formed and the photoelectric conversion layer was exposed was used.

[0519] Specifically, the durability of the perovskite solar cell was evaluated by observing the decomposition of the perovskite crystal in the photoelectric conversion layer while the above-mentioned laminate was placed in an environment of 23°C, 50% relative humidity, and 20.9% ± 0.2% oxygen concentration.

[0520] A photoelectric conversion layer with the desired power generation capacity has a metallic luster, while a photoelectric conversion layer whose power generation capacity has decreased or has no power generation capacity due to the decomposition of the perovskite crystal does not have a metallic luster. The decomposition products of the perovskite crystal exhibit a pale yellow to translucent white color. For these reasons, the durability of a perovskite solar cell can be evaluated by observing the appearance of the photoelectric conversion layer in an environment of 23°C, 50% relative humidity, and 20.9% ± 0.2% oxygen concentration.

[0521] T50 was defined as the time at which the ratio of the area with metallic luster to the area of ​​the photoelectric conversion layer fell below 50%. T50 was determined for each of the laminates formed using the liquid compositions of Examples 1-3 and Comparative Examples 2-4. T50 was also determined for the laminate formed using the liquid composition of Comparative Example 1. The durability index, as a dimensionless number, was calculated by dividing the T50 of the laminates formed using the liquid compositions of Examples 1-3 and Comparative Examples 1-4 by the T50 of the laminate formed using the liquid composition of Comparative Example 1. Based on the calculated durability index, the durability of the perovskite solar cells of each example and comparative example was evaluated according to the following criteria. The evaluation results are shown in Table 3. Evaluation 1: Index was less than 1. Evaluation 2: Index was 1. Evaluation 3: Index was greater than 1 and less than 1.5. Evaluation 4: Index was 1.5 or greater and less than 2. Evaluation 5: Index was 2 or greater.

[0522]

[0523] Table 3 shows that the durability of the perovskite solar cell of the example, which contains phosphorus pentoxide between the first and second electrode layers, is superior to that of the perovskite solar cell that does not contain phosphorus pentoxide between the first and second electrode layers. Although the mechanism by which the above effect is obtained by adding the specific additive in the present invention is not fully clear, compared to the additive used in Comparative Examples 2 to 7, the phosphorus pentoxide used in Examples 1 to 3 has high dehydration ability, and it is presumed that phosphoric acid is produced by the dehydration reaction, and that the perovskite crystal is stabilized by hydrogen bonding.

[0524] 1 Perovskite solar cell 10 Substrate 20 First electrode layer 30 Hole transport layer 40 Photoelectric conversion layer 50 Electron transport layer 60 Second electrode layer

Claims

The device comprises a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order. Between the first electrode layer and the second electrode layer, one or more compounds selected from the group consisting of ascorbic acid compounds, phenolic compounds, and unsaturated compounds are included. The aforementioned ascorbic acid compound is defined by the following formula (1a): (In formula (1a), R １ , and R ２ Each is independently a hydrogen atom or a monovalent organic group, R ３ R is a hydrogen atom, a monovalent organic group, or an alkali metal atom. ４ (This is a hydrogen atom or a monovalent organic group.) It is a compound represented by the following: The aforementioned unsaturated compound is defined by the following formula (1b) or the following formula (1c): R ５ -CO-O-CH ２ -CH=C(CH ３ ) ２ ・・・(1b) R ６ -O-CHR ７ -CH=C(CH ３ ) ２ ・・・(1c) (In equation (1b), R ５ is a monovalent organic group. In formula (1c), R ６ , and R ７ Each of these is an independently monovalent organic group, R ６ and R ７ (These may be joined together to form a ring.) A perovskite solar cell comprising one or more compounds selected from the compounds represented by [the formula shown]. 　 The perovskite solar cell according to claim 1, wherein ascorbic acid is provided between the first electrode layer and the second electrode layer as a compound represented by formula (1a). 　 Between the first electrode layer and the second electrode layer, the phenolic compounds include 2,6-di-tert-butyl-p-cresol (BHT), p-methoxyphenol, 4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole, 2-tert-butyl-4-hydroxyanisole, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol, 4,4'-thiobis(3-methyl-6-tert-butylphenol), α-tocopherol, bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid](ethylenebisoxy) A perovskite solar cell according to claim 1, comprising one or more selected from the group consisting of ethylene (Irganox 245, manufactured by BASF Japan), pentaerythritol tetrakis[3-[3,5-di(tert-butyl)-4-hydroxyphenyl]propionate], bis[3-[3,5-di(tert-butyl)-4-hydroxyphenyl]propionic acid]thiobisethylene, octadecyl-3-(3,5-di-ter-butyl-4-hydroxyphenyl)propionate, octyl-3-(3,5-di-ter-butyl-4-hydroxyphenyl)propionate, 2,4,6-tris(4-hydroxy-3,5-di-tert-butylbenzyl)mesitylene, and 2,4-bis(octylthiomethyl)-6-methylphenol. 　 The perovskite solar cell according to claim 1, wherein between the first electrode layer and the second electrode layer, the unsaturated compound comprises 3-methyl-2-butenyl acetate and / or 4-methyl-2-(2-methyl-1-propenyl)tetrahydropyran. 　 The perovskite solar cell according to claim 1, wherein one or more of the compounds selected from the group consisting of the ascorbic acid compound, the phenolic compound, and the unsaturated compound are included in the photoelectric conversion layer. 　 The first electrode layer is laminated on a substrate, The shape of the substrate is plate-like or sheet-like, The perovskite solar cell according to any one of claims 1 to 5, wherein the substrate comprises at least one of metal, resin, or glass. 　 The first electrode layer is laminated on a substrate, A perovskite solar cell according to any one of claims 1 to 5, comprising a silicon semiconductor substrate as the substrate. 　 (A) Lead halides and / or tin halides, (B) Formamidine hydrohalides, and / or methylamine hydrohalides, (C) Organic solvents, and (D) comprising one or more compounds selected from the group consisting of ascorbic acid compounds, phenolic compounds, and unsaturated compounds, The aforementioned ascorbic acid compound is defined by the following formula (1a): (In formula (1a), R １ , and R ２ Each is independently a hydrogen atom or a monovalent organic group, R ３ R is a hydrogen atom, a monovalent organic group, or an alkali metal atom. ４ (This is a hydrogen atom or a monovalent organic group.) It is a compound represented by the following: The aforementioned unsaturated compound is defined by the following formula (1b) or the following formula (1c): R ５ -CO-O-CH ２ -CH=C(CH ３ ) ２ ・・・(1b) R ６ -O-CHR ７ -CH=C(CH ３ ) ２ ・・・(1c) (In equation (1b), R ５ is a monovalent organic group. In formula (1c), R ６ , and R ７ Each of these is an independently monovalent organic group, R ６ and R ７ (These may be joined together to form a ring.) A liquid composition for forming a photoelectric conversion layer in a perovskite solar cell, comprising one or more compounds selected from the compounds represented by [the formula]. 　 The liquid composition according to claim 7, comprising one or more selected from the group consisting of (E) cesium halide, (F) passivation material, and (G) hole transport material. 　 A method for manufacturing a perovskite solar cell comprising a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order, A method for producing the photoelectric conversion layer by removing volatile components from a coating film containing the liquid composition described in claim 8 or claim 9. 　 The device comprises a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order. Between the first electrode layer and the second electrode layer, there is one or more oxygen atom-containing compounds selected from succinic acid compounds and phosphorus compounds. The succinic acid compound is one of the following formulas (1) to (4): (In equation (1), R １ , and R ６ Each of these is independently a hydrogen atom, a monovalent organic group, or an alkali metal atom. In formulas (1) to (4), R ２ ~R ５ , R ９ ~R １２ , and R １５ ~R ２２ Each is independently a hydrogen atom or a monovalent organic group. In formula (2), R ７ , R ８ , R １３ , and R １４ Each of these is independently a hydrogen atom or a monovalent organic group. ７ , R ８ , R １３ , and R １４ At least one of them is a monovalent organic group. In formula (4), R ２３ (This is a hydrogen atom or a monovalent organic group.) One or more compounds selected from the compounds represented by, The phosphorus compound is of the following formula (I) or the following formula (II): O=P(OR １０ ) ３ ・・・(I)、 P(OR １１ ) ３ ・・・(II) (In formula (I), R １０ Each of these is independently a hydrogen atom, a monovalent organic group, or an alkali metal atom. In formula (II), R １１ These are, independently, a hydrogen atom, a monovalent organic group, or an alkali metal atom. A perovskite solar cell comprising one or more compounds selected from the compounds represented by [the formula shown]. 　 The perovskite solar cell according to claim 11, wherein the oxygen atom-containing compound comprises a dialkyl succinate and / or N-alkylsuccinimide as the succinic acid compound. 　 The perovskite solar cell according to claim 11, wherein the oxygen atom-containing compound comprises one or more compounds selected from the group consisting of phosphoric acid, phosphorous acid, trialkyl phosphate, and trialkyl phosphate as the phosphorus compound. 　 The perovskite solar cell according to claim 11, wherein the oxygen atom-containing compound is included in the photoelectric conversion layer. 　 The first electrode layer is laminated on a substrate, The shape of the substrate is plate-like or sheet-like, The perovskite solar cell according to any one of claims 11 to 14, wherein the substrate comprises at least one of metal, resin, or glass. 　 The first electrode layer is laminated on a substrate, A perovskite solar cell according to any one of claims 11 to 14, comprising a silicon semiconductor substrate as the substrate. 　 (A) Lead halides and / or tin halides, (B) Formamidine hydrohalides, and / or methylamine hydrohalides, (C) Solvent, and (D) Oxygen atom-containing compounds Includes, The (D) oxygen atom-containing compound is one or more selected from succinic acid compounds and phosphorus compounds. The succinic acid compound is one of the following formulas (1) to (4): (In equation (1), R １ , and R ６ Each of these is independently a hydrogen atom, a monovalent organic group, or an alkali metal atom. In formulas (1) to (4), R ２ ~R ５ , R ９ ~R １２ , and R １５ ~R ２２ Each is independently a hydrogen atom or a monovalent organic group. In formula (2), R ７ , R ８ , R １３ , and R １４ Each of these is independently a hydrogen atom or a monovalent organic group. ７ , R ８ , R １３ , and R １４ At least one of them is a monovalent organic group. In formula (4), R ２３ (This is a hydrogen atom or a monovalent organic group.) One or more compounds selected from the compounds represented by, The phosphorus compound is of the following formula (I) or the following formula (II): O=P(OR １０ ) ３ ・・・(I)、 P(OR １１ ) ３ ・・・(II) (In formula (I), R １０ Each of these is independently a hydrogen atom, a monovalent organic group, or an alkali metal atom. In formula (II), R １１ These are, independently, a hydrogen atom, a monovalent organic group, or an alkali metal atom. A liquid composition for forming a photoelectric conversion layer in a perovskite solar cell, comprising one or more compounds selected from the compounds represented by [the formula]. 　 The liquid composition according to claim 15, comprising one or more selected from the group consisting of (E) cesium halide, (F) passivation material, and (G) hole transport material. 　 A method for manufacturing a perovskite solar cell comprising a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order, A method for producing the photoelectric conversion layer by removing volatile components from a coating film containing the liquid composition described in claim 17 or claim 18. 　 The device comprises a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order. A perovskite solar cell comprising phosphorus pentoxide between the first electrode layer and the second electrode layer. 　 The perovskite solar cell according to claim 20, wherein the phosphorus pentoxide is included in the photoelectric conversion layer. 　 The first electrode layer is laminated on a substrate, The shape of the substrate is plate-like or sheet-like, The perovskite solar cell according to claim 20, wherein the substrate comprises at least one of metal, resin, or glass. 　 The first electrode layer is laminated on a substrate, The perovskite solar cell according to claim 20, which is a tandem solar cell comprising a silicon semiconductor substrate as the substrate. 　 (A) Lead halides and / or tin halides, (B) Formamidine hydrohalides, and / or methylamine hydrohalides, (C) Organic solvents, and (D) Phosphorus pentoxide A liquid composition for forming a photoelectric conversion layer in a perovskite solar cell, comprising [a specific compound / component]. 　 The liquid composition according to claim 24, comprising one or more selected from the group consisting of (E) cesium halide, (F) passivation material, and (G) hole transport material. 　 A method for manufacturing a perovskite solar cell comprising a first electrode layer, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a second electrode layer in this order, A method for producing the photoelectric conversion layer by removing volatile components from a coating film containing the liquid composition described in claim 24 or claim 25.

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